Sanctification

After we become believers, our walk with God begins with sanctification as result.

1) Some of those who come to faith leave God for various reasons.

It may be because they are moving away from the Christian environment they participated in. It may be because they are losing their Christian faith, perhaps as a result of lack of guidance and instruction in God's word. Regardless of the time in life when one makes the decision to accept Christ, there is always a need for discipleship and instruction in God's word. Another reason may be because they want to live in the world rather than with God. The Bible says the following about it:

"For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overcome, the last state has become worse for them than the first. For it would have been better for them never to have known the way of righteousness than after knowing it to turn back from the holy commandment delivered to them." (2 Pet 2:20–21).

Here it's about a person who was a believer, but who deliberately turned away from God to live in the world (2 Cor 6:1). A warning example is Judas who even betrayed Jesus, see Why Judas betrayed Jesus.

2) Others want to belong to God but think they can live a life of sin.

They live by the phrase "once saved, always saved", and think it's OK to live a life of sin as a Christian. See this explained in the following videos:

• Hebrews 6:1-6 Explained | Once Saved Always Saved Theology Destroyed.
• 100% Proof You Can Lose Your Salvation | Romans 11:17–22.
• Time 16:55-28:22 in This BIG Lie of Satan Sends Believers to Hell.

From these Bible words, it is clear that it is not OK to live a life of willful sin and still be counted as a Christian:

• "For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful expectation of judgment, and a fury of fire that will consume the adversaries. Anyone who has set aside the Law of Moses dies without mercy on the evidence of two or three witnesses. How much worse punishment, do you think, will be deserved by the one who has trampled underfoot the Son of God, and has profaned the blood of the covenant by which he was sanctified, and has outraged the Spirit of grace?" (Heb 10:26–29). 
  This is about a firm decision to continue sinning without repenting,
  done by a saved person, even though he knows it's against God's will.
  See Do You lose Your Salvation After Sinning Willfully? Hebrews 10:26.
• "Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. But exhort one another every day, as long as it is called 'today', that none of you may be hardened by the deceitfulness of sin. For we have come to share in Christ, if indeed we hold our original confidence firm to the end. As it is said, 'Today, if you hear his voice, do not harden your hearts as in the rebellion.' 
  For who were those who heard and yet rebelled? Was it not all those who left Egypt led by Moses? And with whom was he provoked for forty years? Was it not with those who sinned, whose bodies fell in the wilderness?
  And to whom did he swear that they would not enter his rest, but to those who were disobedient? So we see that they were unable to enter because of unbelief." (Heb 3:12–19, 1 Cor 15:1–2).
• "Not everyone who says to me, 'Lord, Lord', will enter the kingdom of Heaven, but the one who does the will of my Father who is in Heaven.
  On that day many will say to me, 'Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?' And then will I declare to them, 'I never knew you; depart from me, you workers of lawlessness.'" (Mat 7:21–23). 
  See Prophecy in Spiritual Gifts.

If a righteous person turns away from his righteousness and begins to sin, he will die (Ezekiel 18:24), see The Book of Ezekiel. This can be compared to a person who is righteous through his faith in Jesus, but then begins to sin deliberately without repenting. On the other hand, it's important that we don't fall under the Law
(Gal 5:4). But then the question is what is meant by sin? Not being circumcised is
no sin in the New Covenant explained in the New Testament, see Jesus and the Law.

The following are examples of sins in the New Covenant that lead to being lost forever, unless repenting. People who do this must repent and pray to God to strengthen them so that they can say no to such temptations in the future:

• "Or do you not know that the unrighteous will not inherit the kingdom
  of God? Do not be deceived: neither the sexually immoral, nor idolaters,
  nor adulterers, nor men who practice homosexuality, nor thieves,
  nor the greedy, nor drunkards, nor revilers, nor swindlers will inherit the kingdom of God." (1 Cor 6:9–10).
• "Now the works of the flesh are evident: sexual immorality, impurity, sensuality, idolatry, sorcery, enmity, strife, jealousy, fits of anger, rivalries, dissensions, divisions, envy, drunkenness, orgies, and things like these.
  I warn you, as I warned you before, that those who do such things will not inherit the kingdom of God. But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, self-control; against such things there is no law." (Gal 5:19–23).
• "Outside are the dogs and sorcerers and the sexually immoral and murderers and idolaters, and everyone who loves and practices falsehood." (Rev 22:15).
• "Then I saw a great white throne and him who was seated on it. From his presence earth and sky fled away, and no place was found for them. And I saw the dead, great and small, standing before the throne, and books were opened. Then another book was opened, which is the Book of Life. And the dead were judged by what was written in the books, according to what they had done. And the sea gave up the dead who were in it, Death and Hades gave up the dead who were in them, and they were judged, each one of them, according to what they had done. Then Death and Hades were thrown into the lake of fire. This is the second death, the lake of fire. And if anyone’s name was not found written in the Book of Life,
  he was thrown into the lake of fire." (Rev 20:11–15).
• "Then I will draw near to you for judgment. I will be a swift witness against the sorcerers, against the adulterers, against those who swear falsely, against those who oppress the hired worker in his wages, the widow and the fatherless, against those who thrust aside the sojourner, and do not fear me, says the Lord of hosts." (Mal 3:5).
• "For behold, the day is coming, burning like an oven, when all the arrogant and all evildoers will be stubble. The day that is coming shall set them ablaze, says the Lord of hosts, so that it will leave them neither root nor branch." (Mal 4:1).

The way to destruction is broad, while the way to life in God's Heaven is narrow
(Mat 7:13–14), see The Narrow Gate.

There are examples of famous pastors who have been revealed to be living in sin.
It can be their salvation that they are revealed, if it causes them to truly repent, confess their sin to God, and begin to live a sanctified life (Psalm 32:5, 1 John 1:9). These people have been given a second chance. Unless they are exposed while they are still alive and they continue to live in sin without repenting, they may be lost forever. When you make a mistake, realize that you made a mistake, repent, rectify the situation, and get back to what you are supposed to do. Don't waste a lot of time trying to make up for your mistake if God has already forgiven you. Then it's important to also forgive yourself. See Psalm 51: Coming to God when we fail. 

1. A life of sin is incompatible with the life of the Holy Spirit who now dwells in us (Gal 5:17). Believers who succumb to a life of sin will be in constant conflict with the Holy Spirit who dwells in them and will be miserable (Psalm 32:3–4).
2. We have "died to sin" (Rom 6:1–2). We are now dead to the control of the old sin nature that once dominated our behavior. We are now free to follow Christ and make him Lord of our lives. To live in sin would be a complete denial of the freedom Christ won for us on the cross. Living in sin means going back to a life of slavery and bondage to the flesh. See also Typology.
3. Victory over sin is a sign, that we have come to know Jesus and belong to him.
   We know that we have come to know him if we obey his commands
   (1 John 2:3, 2:29, 3:6, 5:18), see Jesus and the Law.
4. Living to please God enables us to test and approve God's will. We should no longer conform to the patterns of this world, but be transformed by the renewing of our minds. Then we will be able to test and approve what God's will is; his good, pleasing and perfect will. (Rom 12:2).
5. We owe Jesus our obedience, gratitude and worship. "I appeal to you therefore, brothers, by the mercies of God, to present your bodies as a living sacrifice, holy and acceptable to God, which is your spiritual worship."
   (Rom 12:1). See How should we worship God? in
   The Woman's Place in the Congregation.
6. Sin always leads to death. Sin can cause death in our lives, even as Christians, when we are careless about allowing sin into our lives. Everything from the death of a marriage, family, and career can easily develop from a life of reckless ignorance. See also The Book of Jude.
1. "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord." (Rom 6:23). 
2. "Then desire when it has conceived gives birth to sin, and sin when it is fully grown brings forth death." (James 1:15). 
3. See Ananias and Sapphira.
7. Because of sin, the wrath of God is coming. "Put to death therefore what is earthly in you: sexual immorality, impurity, passion, evil desire, and covetousness, which is idolatry. On account of these the wrath of God is coming." (Col 3:5–6). See God has wrath in God's Attributes.

If you struggle with this to live a holy life, see time 6:00–13:53 as encouragement
in Titus 3 • Careful to devote ourselves to good works.

See also The Book of Corinthians.

3) Others want to belong to God, and want to live a sanctified life.

When we came to faith in Jesus, by grace trough faith, without works (Eph 2:8–9,
1 Cor 15:1–2) and repented from our sin, we became holy and justified in the sight of God (Heb 10:10). That is, we received positional righteousness, the righteous standing we have before God through Jesus Christ (2 Cor 5:21). This is how God looks at us when we become a follower of Jesus. Practical righteousness is how
I live my life and requires sanctification. We  need to be gradually sanctified in our walk with God (Heb 10:14). Progressive sanctification is a continuous process after receiving Jesus. See this explained at time 33:55–36:01 in 1 Peter 1 (Part 1) :1-2. See also time 22:50–25:12 in May 2024 Bible Q&A.

Note also that a true faith in Jesus results in good works (James 2:18, Eph 2:10), see The Parables of the Talents and the Ten Minas. A natural result of faith is work because my life has changed, but work isn't required to be saved.

If you struggle with this to live a holy life, see time 6:00–13:53 as encouragement
in Titus 3 • Careful to devote ourselves to good works.

God wants us to work out our salvation (Phil 2:12–13). It speaks of making my 
salvation functional in all areas of my life, inviting Jesus to be Lord in more and more areas of everyday life. When we came to Christ, we began our walk with God. From there, the Holy Spirit encourages us to go deeper and deeper into the life of Christ, as far as we are willing to go (Rom 8:4). To do this, he speaks to us about new and different areas where we can surrender control to the Lordship of Jesus Christ. Our marriage, our work, our daily speech, and even our thoughts are affected. And as we concede more and more of these areas of the self-life and surrender them to Jesus, we are said to work out our salvation. We should do it in the same way as we received Jesus as Lord, that's by faith (Col 2:6–8 (NIV), Rom 1:17 (NIV), Gal 3:11, Hab 2:4b), see time 9:59–10:50 in Bible Q & A With Pastor Paul - June 2023.

It's then important to distinguish between Sanctification and Legalism. There is always a risk that a desire to live a sanctified life will tip over into a life of legalism.
See Legalism in The Book of Colossians and Disputable Matters in
The Book of Romans. Legalism ends up in man-made rules and regulations.

Our hearts can't be changed by trying to follow rules and regulations. Our hearts
can only be changed by grace through faith in God and through the work of the 
Holy Spirit in our lives. We must trust God to transform our lives, to believe that he can do in us what we can't do in our own strength. God can take his word, put it into our lives, and change us through the Holy Spirit (John 16:13–15). He can mold us into a closer image of Christ (Rom 8:29). See it explained at time 17:43–25:11 in John 13:1-17 – Prepared to Serve. We shouldn't compare ourselves to other people. To achieve this we need to spend time in the word, in prayer, and in an environment of Christian fellowship. See also: 
Seven elements to make us grow as Christians in The Sermon on the Mount.

As Christians, we have the following help to live our lives:

1. We are all born with a conscience that acts as a gauge of right and wrong. 
   It's a remnant for us being created as the image of God. However, our conscience can be corrupted (1 Tim 4:1–2). It can be influenced by prejudice, superstition, or downright bad teaching. We can be taught to ignore our conscience. We can have a "weak" conscience, see
   Disputable Matters in The Book of Romans. 
2. God's word, the Bible, to help us understand morality.
3. The Holy Spirit who lives in us as born again believers, see Jesus the Light of the World. The process of conviction that the Holy Spirit will place upon us when we get off course. The Holy Spirit doesn't change as the conscience can. He is so far superior to the conscience. He can do the following: 
• Remind us of things we used to know and maybe forgot. 
• Comfort us in difficult times. 
• Counsel us with wisdom and insight in our walk in this life. 
• Remind us of Scripture. 
• He doesn't go against the Scripture (Gal 5:16–17, 19–21a, 26).

However, we can withstand them all. This is called grieving the Holy Spirit. The danger in not responding to the Holy Spirit is that it will be more difficult to respond to him the next time. And pretty soon it's almost impossible to hear his voice.

When Jesus paid the price for our sin on the cross, and we received Jesus as our Lord and Savior, and we began to trust him, God took the work of Jesus on the cross and applied it to us. We then became righteous before God. God sees us in the righteousness of Jesus Christ. Justification happens in an instant. Righteousness isn't a process. Sanctification is a process after we are justified, because we still live in a sinful body. Sanctification is about how we live our Christian life. We should become more and more controlled by the Holy Spirit (John 15:5) to live our lives more for God doing good works and not live in sin. 

It's God's will that we allow ourselves to be sanctified (1 Thess 4:3–8). We can't
do it in our own strength, we need the power of thee Holy Spirit to achieve it 
(1 Thess 5:23a). Salvation is by grace trough faith, and should be followed by being sanctified by the Holy Spirit (2 Thess 2:13). Circumcision in the Old Covenant 
(not applicable in the New Covenant) is a picture of sanctification, see Typology. We should be led by the Holy Spirit and not satisfy the desires of the flesh (Gal 5:16).

After we have been saved, there is a great risk that we still sin in various ways, unintentionally but also intentionally. This isn't God's will. God wants us to live a sanctified life. Sanctification means that we live more and more in obedience to God's word. We need to grow in spiritual maturity. (Psalm 119:11, 2 Pet 3:18). We gain knowledge about Jesus by reading and studying what is written in the Bible. Sanctification is an ongoing work of God in our lives. This is something believers must honestly strive for (1 Pet 1:15–16, Phil 2:12–13). Our actions, but also our thoughts and feelings are part of our sanctification (2 Cor 7:1, Eph 1:3–4).

God the Father has sanctified Jesus and sent him into the world (John 10:36).
The holiness of Jesus is an example for us to follow. If God is to use us, we need
to be sanctified. We will be transformed step by step to become more like Jesus
(Rom 8:29, Gal 4:19, 2 Cor 3:18).

Without sanctification, we may even miss the goal of getting to God's Heaven,
see A New Heaven and a New Earth. Here we are talking about spiritual death
and eternal loss compared to eternal life with God.

• "Strive for peace with everyone, and for the holiness without which no one will see the Lord." (Heb 12:14).
• "But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life. For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord." (Rom 6:22–23). 
• "For if you live according to the flesh you will die, but if by the Spirit you put to death the deeds of the body, you will live." (Rom 8:13)

See To Fear the Lord in in Fear of Man. It's also necessary to forgive anyone who treats us badly, see Forgive and You will Be Forgiven.

What must I do if I know that I have inadvertently or even intentionally done what is wrong before God? Then I must repent. I must humble myself and in prayer admit my shortcomings and ask God for forgiveness (Psalm 32:5, 1 John 1:9). I must not explain away or blame someone else. A good example is king David, who didn't wash away his sin when he deliberately wronged God (2 Sam 11:2–12:25, Psalm 51:1–2, 10 (1–4, 12 in some translations)), see Psalm 51: Coming to God when we fail. 

A good way to not fall for temptation is to read and also study the Bible and learn from God's people mentioned in the Bible. See The Book of John and 
The Book of Hebrews. One can also imagine what the reward will be one day by following God (Gal 6:9–10). It's a short time we live on Earth compared to the eternity that awaits us after death.

Sanctification is a gradual work by God in us (2 Cor 3:18), based on daily decisions by faith to work it out (Eph 4:22–24). It's not done automatically. See the following guidelines given by king David in Psalm 101: How to live a holy life.

Dangers to avoid as Christians in doing this are as follows:

1. To show no mercy:
   God wants us to be a people of mercy and forgiveness. Mercy triumphs over judgment (James 2:13). See examples of showing mercy at the end part of The Book of Ruth.
2. Decisions or lack of decisions based on fear:
   We must be aware of the many times we make decisions or lack of decisions
   based on fear, see Fear of Man. We may not even be aware of it. God didn't give us a spirit of fear but of power, love, and self-control (2 Tim 1:7). Fear is the opposite of faith, it's the absence of faith. Fear of people is a sin that we can confess to God for forgiveness, help, and strength against.
3. Assume the worst about others:
   Gossip has done much harm in the body of Christ. When we hear something
   about a Christian brother or sister, we can believe the worst without having the facts. Gossip can destroy people's faith. There are examples of people not attending Christian meetings or fellowships because they have been wounded in the body of Christ, and that because of careless assumptions.
   (1 Cor 13:4–7). In the same way we judge others, we will be judged,
   see Do not judge others in The Sermon on the Mount.

The principles to follow are the following:

1. Obedience:
   We need to walk with God in an attitude of obedience, see Jesus and the Law.
   We need to live it out in the power of the Holy Spirit. Once we are forgiven
   and saved (see Salvation), then is time to walk in obedience to the Lord,
   see The Narrow Gate. 
2. Separation:
   We are called to a separation from a lifestyle in the world. We must live in the world but not according to the world's lifestyle and values. We shouldn't have idols in our lives, see the 1st commandment in The Ten Commandments.
   We must pray to God to deliver us from these things. 
   We can't take anything with us when we die, see
   Laying up treasures in Heaven in The Sermon on the Mount.
3. Love of God:
   This is the most important principle, see The Golden Rule in
   The Sermon on the Mount. Lack of love for God results in lack of obedience and lack of separation to the world. One way to do that is to constantly be reminded of what he has done for us, see The Crucifixion of Jesus.
   We forget that God is there to help us to love him, to restore our love relationship.

We need the power of the Holy Spirit to do this and to live a sanctified life,
see time 0:36–3:10 and 4:26–6:38 in Bible Q&A with Pastor Paul │ October 2023.

See also Some stories close related to the gospels at the end of 
The Four Gospels.

The Atonement

Content:

• General
• The Old Covenant in the Bible
• The New Covenant in the Bible
• Salvation
  
  

General

Atone or Atonement means:

• To cover up.
• Pacify.
• Make propitiation. This word means: turn away wrath.

Adam and Eve disobeyed God and instead believed in Satan, see 

The Biblical Creation and the Fall of Man. Through Adam, sin entered the world. 
We all need atonement, for we have all sinned. (Rom 5:12). Sin completely separates us from God and his love for us. God's plan to save us from our sin involved God the Father sending his only Son to die on a wooden cross. 

God set up a system to remind his people of how bad their sin was by incorporating animal sacrifices. He did this because every time an animal was killed they would be reminded that the wages of sin is death (Rom 6:23). Without the shedding of blood there is no forgiveness of sins (Heb 9:22). However, the blood of goats and bulls could never pay the price for our sin (Heb 10:11). Animal sacrifices were used to foreshadow a very special sacrifice that was yet to come, when God the Father
offered his only Son, Jesus Christ. Until it was time for Jesus to come, God reminded his people every day that sin causes death, and it's only through death that we can have eternal life. Although animal sacrifice shows how terrible our sin really is, it also shows how deep and wonderful God's love is for us. It shows how far God was willing to go for us to be saved.

God is the creator of the universe and everything in it, he is the sovereign judge of his creation. God is absolutely holy and righteous, without fault or sin. When we sin, we sin against God, he is the offended part. There is a relationship problem between us and God because of our sin. God can’t have fellowship with sin. As the righteous judge of all, he must condemn sin. Because he is absolutely pure, righteous, and holy, he condemns all sin to death. All sin is worth death. Someone must die because of our sin. God is never soft on sin. Mercy isn't a contradiction of judgement. When God shows mercy, kindness, or love, he is no less just.

God is good, all good things come from God, but God is also holy. God loves the sinner because of his goodness but hates our sin because of his holiness, see 
God is holy and God has wrath in God's Attributes. The natural response to sin for God is therefore wrath, see the wrath of God in Balaam and Balak. 

Forgiveness is a big problem for God. The problem of forgiveness is the inevitable collision between divine perfection and human rebellion, between God as he is and us as we are. Forgiveness is for man the simplest of duties, for God it's the deepest of problems. To us forgiveness may not be a big deal, but to God it's a big deal. The reason for this is that God is so perfectly holy. But he is also perfectly love. Both his holiness and his love must be satisfied. God must find a way to forgive us as sinners without compromising his attributes, see God's Attributes. (Isaiah 45:21b).

God therefore introduced the concept of sacrifice. The purpose was to turn away God's wrath because of our sin. God accepted the death of animals as an entry for humans into the Old Covenant. God also understood that the people wouldn't be able to follow the Mosaic Laws of the Old Covenant and therefore needed forgiveness when they failed to do so. It was a sin to disobey these Laws.

God forgave these individuals their sin when they sacrificed the animals because they exercised faith. But it was only a temporary provision. These sacrifices couldn't wipe out sin. It 's impossible for blood of bulls and goats to take away sin
(Heb 10:4). These animal sacrifices pointed to a greater sacrificial death to come, the death of Jesus Christ. This means that all sins before Christ went unpunished
(Rom 3:25), even though the people had been temporarily forgiven, see this explained at time 51:06–53:56 in Bible Q&A With Pastor Paul │March 2024.
Jesus therefore had to die for our sins, to make it possible for us to be saved.

The sin of the Old Covenant individual was temporarily covered by sacrifice of animals. But the sins remained unpunished. All sins committed up to the time of Christ went unpunished, only temporarily covered by the animal sacrifices. The sins were forgiven by the animal sacrifices, but unpunished. Animals can't be punished as stand-ins for humans. God took care of it, once and for all, when Jesus Christ died on the cross. Jesus then bore every sin from the time of Adam (see The Biblical Creation and the Fall of Man) until that day, and for every sin committed thereafter.
This was God's righteous judgment.

The solution is therefore: In Christ, God reconciled the world to himself 
(2 Cor 5:19, 21). One more action is required of us to activate this reconciliation
(2 Cor 5:18, 20b), see Salvation.

The Old Covenant in the Bible
(described in the Old Testament):

Animal sacrifice was practiced in the Old Testament long before the Old Covenant with the sacrificial system was introduced:

"In the course of time Cain brought to the Lord an offering of the fruit of the ground, and Abel also brought of the firstborn of his flock and of their fat portions. And the Lord had regard for Abel and his offering, but for Cain and his offering he had no regard. So Cain was very angry, and his face fell." (Gen (1 Mos) 4:3–5). 

Abel sacrificed his firstborn in his flock. It was a foreshadowing of the coming Christ.

One explanation for why God looked at Abel's sacrifice and not Cain's is that Abel's sacrifice was an animal sacrifice with blood (Heb 12:24). This wasn't the reason. Another more reasonable explanation is that Abel offered a better sacrifice than
Cain, because he offered it by faith (Heb 11:4, 6). See this explained at times:

• 10:00–13:23 in Hebrews 11 (Part 2) :2-7 • Without Faith . . .. 
• 11:05–13:55 in DAVID GUZIK SERMON ON Hebrews 11:1-16 . . ..
• 8:57–18:38 in DAVID GUZIK SERMON ON GENESIS 4 CAIN, ABEL . . ..

"Then Noah built an altar to the Lord and took some of every clean animal and some of every clean bird and offered burnt offerings on the altar. And when the Lord smelled the pleasing aroma, the Lord said in his heart, 'I will never again curse the ground because of man, for the intention of man’s heart is evil from his youth. Neither will I ever again strike down every living creature as I have done. While the Earth remains, seedtime and harvest, cold and heat, summer and winter, day and night, shall not cease.'" (Gen (1 Mos) 8:20–22).

After the Flood, Noah sacrificed some of the clean animals.

"And Isaac said to his father Abraham, 'My father!' And he said, 'Here I am, my son.' He said, 'Behold, the fire and the wood, but where is the lamb for a burnt offering?' Abraham said, 'God will provide for himself the lamb for a burnt offering, my son.' So they went both of them together. When they came to the place of which God had told him, Abraham built the altar there and laid the wood in order and bound Isaac his son and laid him on the altar, on top of the wood. Then Abraham reached out his hand and took the knife to slaughter his son. But the
Angel of the Lord called to him from Heaven and said, 'Abraham, Abraham!' And he said, 'Here I am.' He said, 'Do not lay your hand on the boy or do anything to him, for now I know that you fear God, seeing you have not withheld your son, your only son, from me.'" (Gen (1 Mos) 22:7–12).
This event describes Abraham's test to see if he loved God so much that he was willing to sacrifice his chosen son Isaac for him. Verse 8 (the bold text) can also be seen prophetically when God the Father later sent Jesus to Earth, the only begotten 
Son of God, as a sacrificial Lamb of God for our sins, see 
The Order between Jesus and the Father in the Trinity

In the Old Covenant, it was a question of animal sacrifice where the animals died in the place of man, see Moses; Part 14: Sacrificial System:

"Your lamb shall be without blemish, a male a year old. You may take it from the sheep or from the goats, and you shall keep it until the fourteenth day of this month, when the whole assembly of the congregation of Israel shall kill their lambs at twilight. Then they shall take some of the blood and put it on the two doorposts and the lintel of the houses in which they eat it." (Exo (2 Mos) 12:5–7).

"The blood shall be a sign for you, on the houses where you are. And when I see the blood, I will pass over you, and no plague will befall you to destroy you, when I strike the land of Egypt." (Exo (2 Mos) 12:13).
Every firstborn died in Egypt, even all the firstborn among the cattle died. The blood saved the people of Israel from suffering because they obeyed God's directives.

Lev (3 Mos) 4 describes the Sin Offering in the Tabernacle of the congregation:

• If the anointed priest unintentionally sins in any of the Lord's commandments and thus brings guilt upon the people, he shall offer for sin that he has committed a bull from the herd without fault to the Lord as a Sin Offering. He shall dip his finger in the blood and sprinkle some of the blood seven times before the Lord before the veil of the sanctuary, and put some of the blood on the horns of the altar of fragrant incense, and all the rest of the blood of the bull he shall pour out at the foot of the altar of burnt offering which is at the entrance to the Tent of Meeting.
  (Verse 2–3, 5–7). 
• If all the congregation of Israel sin unintentionally, then the anointed priest shall dip his finger in some of the blood of the bull and sprinkle it seven times before the veil, and put some of the blood on the horns of the altar that is in the Tent of Meeting and the rest of the blood he shall pour out at the foot of the altar of burnt offering which is at the entrance to the
  Tent of Meeting. (Verse 13, 16–18).
• When a leader sins unintentionally, the priest shall take some of the blood of the Sin Offering with his finger and put it on the horns of the altar of burnt offering and pour out the rest of the blood at the foot of the altar of burnt offering. (Verse 22, 25).
• If any of the common people sins unintentionally, the priest shall take some of the blood with his finger and put it on the horns of the altar of burnt offering, and pour out all the other blood at the foot of the altar.
  (Verse 27, 30).
• If anyone wants to offer a lamb as a Sin Offering, he must bring an unblemished female animal. Then the priest shall take some of the blood of the Sin Offering with his finger and put it on the horns of the altar of
  burnt offering and pour out all the other blood at the foot of the altar. 
  (Verse 32, 34).

See also Sin Offering in Moses; Part 14: Sacrificial System.

It's the sinner who brings the sacrificial animal, but it's the priest who brings atonement through the blood. Two are involved. 

When the priest brings reconciliation in this way, the sinner is forgiven. It's obtained through the blood sacrifice of certain animals. The life of a creature is in the blood (Lev (3 Mos) 17:11). Without blood, there is no forgiveness, that is,
no reconciliation (Heb 9:22). It's not enough to just ask God for forgiveness without blood sacrifice. The blood satisfies God's wrath against sin.

Lev (3 Mos) 16 describes how the rules for entering the Most Holy Place of the Tabernacle were changed. This change was introduced after two of Aaron's sons
had died because they had brought unauthorized fire before the Lord, something
he hadn't commanded them to do (Lev (3 Mos) 10:1–2), see
The Death of Nadab and Abihu in Moses; Part 12: The Aaronic Priesthood.
No part of the regular Sin Offering should be made in the Most Holy Place of the Tabernacle. God would appear in the cloud on the atonement cover (mercy seat),
which formed the cover of the ark (the Ark of the Covenant), placed in the 
Most Holy Place (verse 2). It should only be the High Priest (Aaron as the first)
who performed the Sin Offering in the Most Holy Place of the Tabernacle and
only once a year. The High Priest would then make atonement twice.
The first time for himself, and the second time for the people of Israel.
(Verse 11, 14–16, 18–19, 27, 32–34). See also Heb 13:11–12). 

This means that only the High Priest makes atonement in the sanctuary once a year, on the Day of Atonement; Yom Kippur, the holiest day in Judaism.

For information about the High Priest, see The High Priest in the Bible.

These sacrifices can no longer be made by the Jewish population around the world after the destruction of the Temple in 70 AD. For them is the Day of Atonement a day of prayer. There are certain ritual prayers that are said on this day, and this is the time when a person can go before God and confess his sin. They then think they are forgiven because they ask for forgiveness. No blood is then involved. There is no sacrificial system going on in Israel in our day to remind them that the forgiveness of sins is based on the shedding of blood (Heb 9:22).

The New Covenant in the Bible
(described in the New Testament):

The priesthood that was under the Mosaic Laws in the Old Covenant, is replaced by a new High Priest in a New Covenant (Heb 7:11–12, 18–19). Jesus fulfilled the Laws that were under the Old Covenant (Mat 5:17). He is the new High Priest forever
(Heb 5:5–6, 6:20, 7:20–21, Psalm 110:4). Animal sacrifices under the Old Covenant
Laws can't save us. The sin was treated at the Day of Atonement but only temporarily for a year, and after that the animal sacrifices must be repeated again. The penalty must still be paid. The old sacrificial system wasn't meant to forgive sins completely, but to point to someone who must die on our behalf, who must come in the future. That someone is Jesus Christ, who had to die physically for our sins, see The Crucifixion of Jesus. He is the High Priest who is holy, innocent, blameless, separated from sinners, and exalted above the heavens (Heb 7:26). 
He only needed to give his life once for our sins (Heb 7:27). 

For more information, see Jesus and the Law.

 

"The Law and the Prophets were until John; since then the good news of the kingdom of God is preached, and everyone forces his way into it." (Luk 16:16).

See also Listen to Jesus. The Day of Atonement in the Old Covenant had to be completed in accordance with the Torah (Pentateuch or Five Books of Moses),
that is, the books: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. 
It was part of the Mosaic Laws and had its time until Jesus officially created the 
New Covenant, when he distributed bread and wine to the disciples as a reminder
to him (Luk 22:20, Jer 31:31–33). This New Covenant was activated when Jesus died on the cross.

"For the Law was given through Moses; grace and truth came through Jesus Christ" (John 1:17). "The next day John the Baptist saw Jesus coming toward him, and he said: 'Behold, the Lamb of God, who takes away the sin of the world!'"
(John 1:29). "John the Baptist looked at Jesus as he walked by and said,
'Behold, the Lamb of God!'" (John 1:36). 
The only way Jesus could take away sin was by shedding his blood as a sacrifice for our sins. Jesus would give his life and be slaughtered like a lamb. 
John the Baptist therefore calls Jesus the Lamb of God, see John the Baptist
in The Prophecies of Isaiah.

In the Old Covenant of the Jews, the High Priest goes once a year and offers blood for himself and for the unintentional sins of the people. When Christ appeared as High Priest, he entered once for all into the holy places, not with the blood of goats and calves, but with the help of his own blood, thus securing an eternal redemption. (Heb 9:6–12). Jesus is therefore the mediator of a New Covenant, so that those who are called may receive the promised eternal inheritance, because a death has occurred which redeems them from the transgressions committed under the first covenant. (Heb 9:15). According to the Law, almost everything is cleansed with blood, and without the shedding of blood there is no forgiveness of sins. Thus it was necessary that the copies of the heavenly things be purified with these rites, but the heavenly things themselves with better sacrifices than these. For Christ has entered, not into holy places made with hands which are copies of the true, but into Heaven itself, to now appear in the presence of God on our behalf. (Heb 9:22–24). This isn't just a picture of what Jesus did on the cross for us, when he shed his blood when he died physically on the cross so that our sins could be forgiven. There is also a tabernacle in God's Heaven (Heb 8:1–2, 5, 9:24, Rev 7:15, 11:19, 15:5–8 (NIV), Isaiah 6:1). Jesus entered there the Most Holy Place once and for all with his own blood and thereby obtained eternal redemption (Heb 6:19–20, 9:11–12).
Jesus did that, probably during the time that Jesus' physical body was in the tomb, see The Resurrection of Jesus. Without the shedding of blood there is no forgiveness (Heb 9:22b). Therefore, Jesus had to die physically on the cross.
See this explained at the following times in these videos:

• 8:41–9:31 in DAVID GUZIK SERMON ON Hebrews 8.
• 21:31–23:28 in DAVID GUZIK SERMON ON Hebrews 9:1-15.
• 8:41–13:50 in Bible Q&A with Pastor Paul.

The basis of what Jesus did for us on the cross is found in Genesis, see it explained in time 4:17–20:02 in Understanding Genesis || Guest Speaker Dr. Jason Lisle.

Jesus fulfilled the Mosaic Laws. Animal sacrifice is no longer needed.
(Heb 10:1, 3–7, 10–12, 14).

"In Jesus we have redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace." (Eph 1:7). "Now in Christ Jesus you who once were far off have been brought near by the blood of Christ." (Eph 2:13). 

"Knowing that you were ransomed from the futile ways inherited from your forefathers, not with perishable things such as silver or gold, but with the precious blood of Christ, like that of a lamb without blemish or spot." (1 Pet 1:18–19).
We are redeemed by the blood of Jesus and have been forgiven for our sins.

Boaz was a kinsman redeemer to Naomi and Ruth, as he was a close relative of theirs, see The Book of Ruth. A kinsman redeemer in the Old Covenant is a picture of Jesus, who is our kinsman redeemer (Isaiah 59:20), see Typology.

A kinsman redeemer must meet the following:

1. He must be a relative by blood (Lev (3 Mos) 25:25, 47–49). 
   God must become a man in order to redeem us from sin. Only one man
   can die for the sin of mankind. The Redeemer must be one of us (Gal 4:4–5).
2. He himself must be free in order to free someone else from slavery. 
   Jesus had to be a sinless redeemer (John 8:46, Heb 4:15, 1 Pet 2:22,
   2 Cor 5:21). If he had sinned, he would have had to pay for his own sin
   and be disqualified from paying for anyone else's sin. Hence The Virgin Birth
   is so important. See time 10:53–14:16 in 1 John 4:1–6 • Test the spirits.
3. He had to have means of redemption. He must be able to do it. 
   We have been redeemed through the blood of Jesus Christ (1 Pet 1:18–21).
4. He had to perform redemption willingly.
   Jesus willingly paid the price for our sins on the cross (John 10:17–18).

"We rejoice in God through our Lord Jesus Christ, through whom we have now received reconciliation." (Rom 5:11). The atonement is received by believing
in Jesus and what he has done for us:

• It’s about God's grace (Rom 3:23–24).
• Faith without works (Rom 3:28).
• Through the blood of Jesus who redeemed us from our sins (Rom 5:9).

See also What Happens to Those Who Have Never Heard About Jesus?

Salvation

This salvation from God's wrath over our sins, through reconciliation with God, 
is based on the following:

• God's grace:
  God the Father loved men so much that he gave his only Son to take away man's sin (John 3:16), see The Order between Jesus and the Father in the Trinity. Jesus, the Son of God, voluntarily took upon himself the sin of man in his physical death (Eph 2:5b, 8).
• Blood of Jesus:
  The blood of Jesus cleanses us from all sin (1 John 1:7, Rev 1:5b).
• Our belief:
  That we believe in Jesus Christ as the Son of God, that we trust him.
  That we believe that he has shed his blood and died on the cross for us, bearing our sins on the cross (John 14:6) and that God (The Trinity) 
  has  raised him from the dead. Faith isn't work (Rom 3:27–28, 
  Eph 2:8–9, Titus 3:4–7). We can’t be justified and saved by our own works or by being good enough. Believing is a decision we make. We must receive Jesus into our heart (John 1:12). Righteousness is imputed to us by doing so. It means getting a right standing with God. We haven't
  earned it, it has been given to us as a free gift when we come to Christ
  (Isaiah 61:10). It's the righteousness of Christ that we literally put on almost like clothing. When we approach God, he receives us in the 
  righteousness of Jesus Christ, see The Parable of the Wedding Feast.
• Repentance:
  We also need to repent (Acts 17:30–31, Luk 13:2–3) because we are all sinners (Rom 5:8, 1 John 1:8–10).

For detailed information on how to be saved, see Salvation.

See also Some stories close related to the gospels at the end of 
The Four Gospels.