Commentaries:
Jamieson, Fausset, and Brown
"Every unrighteousness (even that of believers, compare I John 1:9; I John 3:4. Every coming short of right) is sin"; (but) not every sin is the sin unto death.
and there is a sin not unto death—in the case of which, therefore, believers may intercede. Death and life stand in correlative opposition (I John 5:11-13). The sin unto death must be one tending "towards" (so the Greek), and so resulting in, death. ALFORD makes it to be an appreciable ACT of sin, namely, the denying Jesus to be the Christ, the Son of God (in contrast to confess this truth, I John 5:1, I John 5:5), I John 2:19, I John 2:22; I John 4:2-3; I John 5:10. Such wilful deniers of Christ are not to be received into one's house, or wished "God speed." Still, I think with BENGEL, not merely the act, but also the state of apostasy accompanying the act, is included—a "state of soul in which faith, love, and hope, in short, the new life, is extinguished. The chief commandment is faith and love. Therefore, the chief sin is that by which faith and love are destroyed. In the former case is life; in the latter, death. As long as it is not evident (see on I John 5:16, on 'see') that it is a sin unto death, it is lawful to pray. But when it is deliberate rejection of grace, and the man puts from him life thereby, how can others procure for him life?" Contrast James 5:14-18. Compare Matthew 12:31-32 as to the wilful rejection of Christ, and resistance to the Holy Ghost's plain testimony to Him as the divine Messiah. Jesus, on the cross, pleaded only for those who KNEW NOT what they were doing in crucifying Him, not for those wilfully resisting grace and knowledge. If we pray for the impenitent, it must be with humble reference of the matter to God's will, not with the intercessory request which we should offer for a brother when erring.
Other Jamieson, Fausset, and Brown entries containing 1 John 5:17:
1 John 5:18
DISCLAIMER: Church of the Great God (CGG) provides these resources to aid the individual in studying the Bible. However, it is up to the individual to "prove all things, and hold fast to that which is good" (I Thessalonians 5:21). The content of these resources does not necessarily reflect the views of CGG. They are provided for information purposes only.