Hebrews 6:1 Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection; not laying again the foundation of repentance from dead works, and of faith toward God, 2 Of the doctrine of baptisms, and of laying on of hands, and of resurrection of the dead, and of eternal judgment. 3 And this will we do, if God permit. 4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost, 5 And have tasted the good word of God, and the powers of the world to come, 6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame. 7 For the earth which drinketh in the rain that cometh oft upon it, and bringeth forth herbs meet for them by whom it is dressed, receiveth blessing from God: 8 But that which beareth thorns and briers is rejected, and is nigh unto cursing; whose end is to be burned. 9 But, beloved, we are persuaded better things of you, and things that accompany salvation, though we thus speak. 10 For God is not unrighteous to forget your work and labour of love, which ye have shewed toward his name, in that ye have ministered to the saints, and do minister. 11 And we desire that every one of you do shew the same diligence to the full assurance of hope unto the end: 12 That ye be not slothful, but followers of them who through faith and patience inherit the promises. 13 For when God made promise to Abraham, because he could swear by no greater, he sware by himself, 14 Saying, Surely blessing I will bless thee, and multiplying I will multiply thee. 15 And so, after he had patiently endured, he obtained the promise. 16 For men verily swear by the greater: and an oath for confirmation is to them an end of all strife. 17 Wherein God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath: 18 That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us: 19 Which hope we have as an anchor of the soul, both sure and stedfast, and which entereth into that within the veil; 20 Whither the forerunner is for us entered, even Jesus, made an high priest for ever after the order of Melchisedec.
Classic example of taking a text in its context in order to prevent pretext.
First and foremost we must understand that repentence is not just sorrow for sinning. In the context of what the Lord Jesus and John the Baptist preached it was the turning away from dead works. This is pivotal, because the Law with regard to salvation had fulfilled its purpose (as the entirety of the book of Hebrews tells us as a divinely inspired commentary on Jeremiah 31:31-34).
To recap:
Galatians 3:24 Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith.
Romans 3:31 Do we, then, nullify the law by this faith? Not at all! Rather, we uphold the law.
The Law still stands but only for judgment.
2 Corinthians 3:6 He has made us competent as ministers of a new covenantnot of the letter but of the Spirit; for the letter kills, but the Spirit gives life.
The spirit of the Law is that no man can save himself because the minimum requirement is too far out of our reach (Isaiah 64:6 note our righteousness is as filthy rags). The letter of the Law is the judgment (the soul that sins shall die or put another way see John 3:18).
Jesus came to make the one sacrifice to save man from death / eternal damnation. This is the foundation of the New Covenant which supercedes the Old. Remember the repentence in Hebrew 6 is from dead works (trying to keep the Law). So what Hebrews 6 is saying, if you taste of the New Covenant and draw back to the Old Covenant there is no other sacrifice for sins.
God progressively reveals truth to us. And to try to revert back to an earlier stage of that progression is a major faux pas. Remember Lot's wife. Remember the Israelites in the wilderness who wanted to return to Egypt. Remember Joshua at the battle of Ai. Remember Elijah who returned to Mount Horeb.
In Matthew 12:31 the blasphemy of the Holy Spirit which will never be forgiven was pronounced (not only for the Pharisees' stubborness in clinging to the Old Covenant, but in their clinging to it to the point that they took what Jesus said and did to authenticate his Messiahship and attribute them to the devil... in order not to believe in him and to teach others not to believe in him). Also, in that chapter of Matthew, I would say that there indeed comes a time when it is too late. We'd like to think it's never to late to .... (fill in the blank) in life. But there comes a time when the offer to be saved stops.
Doctor Donald Grey Barnhouse once said "We must remember that the book of Hebrews was written to Hebrews. And that it was written to the Hebrews to tell them to stop being Hebrews and to become Christians."
We cannot equate from Hebrews 6 an eternal damnation for any and all who fall away in the least. Look at the difference between Peter and Judas. Peter fell away. There is no doubt. He denied the Lord even though he was told it was coming. But he did not return to Judaism. He ran to the empty tomb. Judas went to the priests to confess his sin.
Regards.
25 But after that faith is come, we are no longer under a schoolmaster.