Charles Ellicott Commentary John 16:8

"And he, when he is come, will convict the world in respect of sin, and of righteousness, and of judgment:" — John 16:8 (ASV)

And when he is come, he will reprove the world.—Better, as in the margin, convince the world. (John 8:46.) The only other passages where it occurs in the Gospels are in Matthew 18:15 and Luke 3:19. It is not in the better reading of John 8:9; but it occurs not infrequently in the Epistles. (See especially the note on 1 Corinthians 14:24.) This conviction of the world is by witness concerning Christ (John 15:26).

It is the revelation to human hearts of the character and work of Christ, and, therefore, a refutation of the evil in their hearts. The result of this conviction is twofold, depending on whether people embrace it, accept its chastening discipline, and are saved by it; or reject it, and in the rejection harden their hearts, and are thus condemned by it. (Compare to 2 Corinthians 2:15–16.) The effect of St. Peter’s sermon on the Day of Pentecost is the first great historical comment on this verse; but the comment is continued in the whole history of the Church’s work. The remainder of the verse enumerates the three steps in this conviction, which are more fully defined in the three following verses.