John Calvin Commentary 2 Corinthians 12:21

"lest again when I come my God should humble me before you, and I should mourn for many of them that have sinned heretofore, and repented not of the uncleanness and fornication and lasciviousness which they committed." — 2 Corinthians 12:21 (ASV)

Lest, when I come, my God should humble me. His humiliation was considered his fault. He throws the blame for it back upon the Corinthians, who, when they should have honored his apostleship, instead loaded it with disgrace. For their spiritual progress would have been the glory and honor of Paul’s apostleship.

Therefore, when they were instead overrun with many vices, they heaped disgrace upon him to the fullest extent. Indeed, he does not charge all of them with this crime, but only a few who had brazenly despised all his admonitions.

The meaning, then, is this: “They think contemptuously of me because I appear contemptible. Let them, then, give me no reason for humiliation; furthermore, let them instead, laying aside their arrogance, begin to feel shame. And let them, confounded by their iniquities, prostrate themselves on the ground, instead of looking down on others with disdain.”

Meanwhile, he lets us know the disposition of a true and genuine pastor when he says that he will look upon the sins of others with grief. And undoubtedly, the right way of acting is this: that every Christian should have the Church enclosed within his heart, and be affected by its maladies as if they were his own, sympathize with its sorrows, and bewail its sins.

We see how Jeremiah entreats that he may be given a fountain of tears, (Jeremiah 9:1), so that he may bewail the calamity of his people. We see how pious kings and prophets, to whom the government of the people was committed, were touched with similar feelings.

Indeed, it is common to all the pious to be grieved whenever God is offended, to bewail the ruin of fellow believers, and to present themselves before God in their place as though guilty; but it is more particularly required of pastors. Furthermore, Paul here brings forward a second list of vices, which, however, belong to one general category—unchastity.