John 16:9

Of sin - Of the sin of the Jews in not receiving me as the Messiah, though my mission was accredited by the very miracles which the prophets foretold: see Isaiah 35:3-6. This was literally fulfilled on the day of pentecost, when the Spirit was given; for multitudes of Jews were then convinced of this sin, and converted to God. See Acts 2:37.

If we take this prediction of our Lord in a more general sense, then we may consider that it is one of the grand offices of the Holy Spirit to convince of sin, to show men what sin is, to demonstrate to them that they are sinners, and to show the necessity of an atonement for sin; and in this sense the phrase, περι ἁμαρτιας, may be understood, and in this sense it is used in multitudes of places in the Septuagint, but the words, because they believe not in me, restrict the meaning particularly to the sin of the Jews in rejecting Jesus as the Messiah.

Of sin - The first thing specified of which the world would be convinced is sin. Sin, in general, is any violation of a law of God, but the particular sin of which men are here said to be convinced is that of rejecting the Lord Jesus. This is placed first, and is deemed the sin of chief magnitude, as it is the principal one of which men are guilty. This was particularly true of the Jews who had rejected him and crucified him; and it was the great crime which, when brought home to their consciences by the preaching of the apostles, overwhelmed them with confusion, and filled their hearts with remorse. It was their rejection of the Son of God that was made the great truth that was instrumental of their conversion. Acts 2:22-23, Acts 2:37; Acts 3:13-15; Acts 4:10, Acts 4:26-28; compare John 16:31-33. It is also true of other sinners. Sinners, when awakened, often feel that it has been the great crowning sin of their lives that they have rejected the tender mercy of God, and trampled on the blood of his Son; and that they have for months and years refused to submit to him, saying that they would not have him to reign over them. Thus is fulfilled what is spoken by Zechariah, Zechariah 12:10; "And they shall look upon me whom they have pierced, and mourn." Throughout the New Testament this is regarded as the sin that is pre-eminently offensive to God, and which, if unrepented of, will certainly lead to perdition, Mark 16:16; John 3:36. Hence, it is placed first in those sins of which the Spirit will convince men; and hence if we have not yet been brought to see our guilt in rejecting God's tender mercy through his Son, we are yet in the gall of bitterness and under the bond of iniquity.

16:9 Of sin - Particularly of unbelief, which is the confluence of all sins, and binds them all down upon us.