Verse 17. - All unrighteousness is sin. "Among the faithful this ought to be an indubitable truth, that whatever is contrary to God's Law is sin, and in its nature mortal; for where there is a transgression of the Law, there is sin and death" (Calvin). But this terrifying truth brings with it a word of encouragement. For if all unrighteousness without exception is sin, it follows that not every sin is unto death. It is incredible that the slightest departure from righteousness should involve eternal damnation (see notes on chapter 1 John 1:7).

5:13-17 Upon all this evidence, it is but right that we believe on the name of the Son of God. Believers have eternal life in the covenant of the gospel. Then let us thankfully receive the record of Scripture. Always abounding in the work of the Lord, knowing that our labour is not in vain in the Lord. The Lord Christ invites us to come to him in all circumstances, with our supplications and requests, notwithstanding the sin that besets us. Our prayers must always be offered in submission to the will of God. In some things they are speedily answered; in others they are granted in the best manner, though not as requested. We ought to pray for others, as well as for ourselves. There are sins that war against spiritual life in the soul, and the life above. We cannot pray that the sins of the impenitent and unbelieving should, while they are such, be forgiven them; or that mercy, which supposes the forgiveness of sins, should be granted to them, while they wilfully continue such. But we may pray for their repentance, for their being enriched with faith in Christ, and thereupon for all other saving mercies. We should pray for others, as well as for ourselves, beseeching the Lord to pardon and recover the fallen, as well as to relieve the tempted and afflicted. And let us be truly thankful that no sin, of which any one truly repents, is unto death.All unrighteousness is sin,.... All unrighteousness against God or man is a sin against the law of God, and the wrath of God is revealed against it, and it is deserving of death; yet all unrighteousness is not unto death, as the sins of David, which were unrighteousness both to God and man, and yet they were put away, and he died not; Peter sinned very foully, and did great injustice to his dear Lord, and yet his sin was not unto death; he had repentance unto life given him, and a fresh application of pardoning grace:

and there is a sin not unto death; this is added for the relief of weak believers, who hearing of a sin unto death, not to be prayed for, might fear that theirs were of that kind, whereas none of them are; for though they are guilty of many unrighteousnesses, yet God is merciful to them and forgives, Hebrews 8:12, and so they are not unto death.