John 16:9

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, Acts 2:37; Acts 3:13; Acts 4:10, Acts 4:26; compare John 16:31. 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.