15 and if we know that he heareth us whatsoever we ask, we know that we have the petitions which we have asked of him. 16 If any man see his brother sinning a sin not unto death, he shall ask, and [God] will give him life for them that sin not unto death. There is a sin unto death: not concerning this do I say that he should make request. 17 All unrighteousness is sin: and there is a sin not unto death.
Matthew Henry's Commentary on 1 John 5:15-17
Commentary on 1 John 5:13-17
(Read 1 John 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.