This extends to things of the greatest importance. If any one see his brother — That is. any man. Sin a sin which is not unto death — That is, any sin but total apostasy from both the power and form of godliness. Let him ask, and God will give him life — Pardon and spiritual life, for that sinner. There is a sin unto death: I do not say that he shall pray for that — That is, let him not pray for it. A sin unto death may likewise mean, one which God has determined to punish with death.
Related Commentaries of 1 John 5:16
1 John 5:16
16 If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.