2 Corinthians 12:21

And lest when I come again
Another thing which he feared would be the case when he came again to them, that he himself should be afflicted and distressed, seeing them in a disorderly and dissolute course of life, be obliged to punish them, which would be an humiliation and matter of grief to him:

my God will humble me;
instead of rejoicing in the fruit of his labours, that they were not in vain, he signifies that he should have great sorrow of heart; and whereas he had promised himself much pleasure and comfort in visiting them, it would be the reverse; and inasmuch as he had boasted of them to others, he should be ashamed:

and that I shall bewail many which have sinned already,
or "before"; not before conversion, but before the writing of this or the former epistle; for nothing was more grieving, and occasioned more sorrow and humiliation to the apostle, than the unbecoming walk of professors; and nothing more sensibly affects a faithful minister of the Gospel:

and have not repented of the uncleanness and fornication, and
lasciviousness, which they have committed.
The city of Corinth was famous, or rather infamous, for unclean practices; as fornication, adultery, lasciviousness in words and deeds, and other unnatural lusts; "Corinthian whores" was a common proverb; nor was it proper for persons to go to Corinth, there were so many snares for lust and uncleanness; there were said to be above a thousand prostitutes in the temple of Venus there ^F11; hence the very great impurities and wickedness, which many of the members of this church were guilty of, may be accounted for; some of them had repented, others not, which was the great concern of the apostle: and from hence we may learn, that gracious souls may be suffered to fall into great sins; and that when they are truly brought to repentance, they ought to be restored to communion with the church; but impenitent ones are to be cut off, and remain so, till brought to a due sense of their evils.