I hope this doesn't side track this thread too much, but here is my two cents on what the sin unto death is.
Sin unto death for me, in simple terms; is to deny Christ (after being given the spirit by faith) by going back to the law.
Gal 3:3 Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?
Heb 6:4 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,
Heb 6:5 And have tasted the good word of God, and the powers of the world to come,
Heb 6:6 If they shall fall away (for me, to revert back to law) , to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame. (for me, this is the sin unto death)
Heb 10:23 Let us hold fast the profession of our faith without wavering; (for he is faithful that promised;)
Heb 10:26 For if we sin willfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
by faith, we won't sin willfully,
Rom 6:14 For sin shall not have dominion over you: for ye are not under the law, but under grace.
1Jo 5:17 All unrighteousness is sin: and there is a sin not unto death.
All sin is forgiven, if living by faith, if the light is shining in us. If we have the light, we see our sin, and confess it.
If we revert back to living by the law, we see no need for Christ, we are blinded by the law, and no longer see our sin.
1Jo 1:8 If we say that we have no sin, we deceive ourselves, and the truth is not in us.
1Jo 1:9 If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness.
We will confess our sins, if by faith, Christ lives in us, by His Light, in us. We are in need of a doctor, we see our sickness.
1Jo 5:4 because every one who is begotten of God doth overcome the world, and this is the victory that did overcome the world--our faith;
1Jo 5:5 Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?
Believing in Him, to me means we believe he is the only way to forgive sins. We rely on him to do this.
1Jo 5:13 These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God.
Gal 2:16 Knowing that a man is not justified by the works of the law, but by the faith of Jesus Christ, even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law: for by the works of the law shall no flesh be justified.
Gal 3:11 But that no man is justified by the law in the sight of God, it is evident: for, The just shall live by faith.
Gal 3:12 And the law is not of faith: but, The man that doeth them shall live in them.
Gal 3:25 But after that faith is come, we are no longer under a schoolmaster.
Gal 4:9 But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage? (this to me is the sin unto death)
Gal 5:1 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.
Gal 5:2 Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing.
Gal 5:4 Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.