There are two kinds of sin recorded in the Bible. Sinning to death and sinning not to death.
1 John 5:16If anyone sees his brother sinning a sin which does not lead to death, he will ask, and He will give him life for those who commit sin not leading to death. There is sin leading to death. I do not say that he should pray about that. 17 All unrighteousness is sin, and there is sin not leading to death.
In the Old Testament it is called willful or presumptous sin and unintentional sin.
Numbers 15:27‘And if a person sins unintentionally, then he shall bring a female goat in its first year as a sin offering. 28 So the priest shall make atonement for the person who sins unintentionally, when he sins unintentionally before the Lord, to make atonement for him; and it shall be forgiven him. 29 You shall have one law for him who sins unintentionally, for him who is native-born among the children of Israel and for the stranger who dwells among them.
30 ‘But the person who does anything presumptuously (open hand-exalt oneself), whether he is native-born or a stranger, that one brings reproach on the Lord, and he shall be cut off from among his people. 31 Because he has despised the word of the Lord, and has broken His commandment, that person shall be completely cut off; his guilt shall be upon him.
32 Now while the children of Israel were in the wilderness, they found a man gathering sticks on the Sabbath day. 33 And those who found him gathering sticks brought him to Moses and Aaron, and to all the congregation. 34 They put him under guard, because it had not been explained what should be done to him.
35 Then the Lord said to Moses, “The man must surely be put to death; all the congregation shall stone him with stones outside the camp.” 36 So, as the Lord commanded Moses, all the congregation brought him outside the camp and stoned him with stones, and he died.
This man was stoned because he committed the sin to dead. He was in open rebellion against the commandment of the Lord.
When we are born again, we have a yes in our spirit, our spirit is willing, but our flesh is weak. So, if we are fulfilling the lust of the flesh, we are miserable. We have a civil war going on inside of us. But we are warned that if we practice the lusts of the flesh, we will not inherit the kingdom. The root of the word sin in the Greek means No-inheritance.
But God is faithful who will chastise us, but if we continue sinning, it can lead to the sin to death. In order for this to happen the light in our spirit has to go out. God has to turn us over to a reprobate mind, where we want nothing to do with God, and we become full of pride, exalting ourselves, and crucifying afresh the son of God.
Hebrews 6: 4 For it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit, 5 and have tasted the good word of God and the powers of the age to come, 6 if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame.
If we sin unto death the Lord will blot our name out of the book of life.
Revelation 3: 5 He who overcomes shall be clothed in white garments, and I will not blot out his name from the Book of Life; but I will confess his name before My Father and before His angels.
When we sin to death, we are twice dead.
Jude 1:12These are spots in your love feasts, while they feast with you without fear, serving only themselves. They are clouds without water, carried about by the winds; late autumn trees without fruit, twice dead, pulled up by the roots; 13 raging waves of the sea, foaming up their own shame; wandering stars for whom is reserved the blackness of darkness forever.
In the Old Testament the person who sinned to death was hanged or stoned.
Deuteronomy 21:22“If a man has committed a sin deserving of death, and he is put to death, and you hang him on a tree, 23 his body shall not remain overnight on the tree, but you shall surely bury him that day, so that you do not defile the land which the Lord your God is giving you as an inheritance; for he who is hanged is accursed of God.
Jesus was hanged on a tree as us. So that when we receive him as our Lord and Savior, we receive the Holy Spirit as a down payment on our inheritance. But we still have a choice to turn our back on God. But we have to continually grieve and quench the Holy Spirit until we get to the place where we no longer care, and there is no room in our heart for repentance.
1 Samuel 12: 20Then Samuel said to the people, “Do not fear. You have done all this wickedness; yet do not turn aside from following the Lord, but serve the Lord with all your heart. 21 And do not turn aside; for then you would go after empty things which cannot profit or deliver, for they are nothing. 22 For the Lord will not forsake His people, for His great name’s sake, because it has pleased the Lord to make you His people. 23 Moreover, as for me, far be it from me that I should sin against the Lord in ceasing to pray for you; but I will teach you the good and the right way. 24 Only fear the Lord, and serve Him in truth with all your heart; for consider what great things He has done for you. 25 But if you still do wickedly, you shall be swept away, both you and your king.”
If we see our brother sinning not to death, we are to pray for him and God will give him life-deliverance.
Saul sinned unto death, and God told Samuel not to pray for him.
1 Samuel 15: 35 And Samuel went no more to see Saul until the day of his death. Nevertheless, Samuel mourned for Saul, and the Lord regretted that He had made Saul king over Israel.
16:1 Now the Lord said to Samuel, “How long will you mourn for Saul, seeing I have rejected him from reigning over Israel? Fill your horn with oil and go; I am sending you to Jesse the Bethlehemite. For I have provided Myself a king among his sons.”