Co 12:19 Again, think ye that we excuse ourselves unto you? we speak before God in Christ: but we do all things, dearly beloved, for your edifying.
2Co 12:20 For I fear, lest, when I come, I shall not find you such as I would, and that I shall be found unto you such as ye would not: lest there be debates, envyings, wraths, strifes, backbitings, whisperings, swellings, tumults:
2Co 12:21 And lest, when I come again, my God will humble me among you, and that I shall bewail many which have sinned already, and have not repented of the uncleanness and fornication and lasciviousness which they have committed.
Old John Gill writes…
though the more abundantly I love you, the less I be loved; though he loved them more than he did other churches, or than the false apostles loved them, and yet were loved by them less than he was by other churches; or by them, than the false apostles were; or rather the meaning is, that though he increased in his love, and in the expressions of it to them, and they grew colder and more indifferent to him, yet this should not hinder his warmest desires and most earnest endeavours after their spiritual and eternal welfare. This way of speaking strongly expresses his love to them, and tacitly implies the lukewarmness of theirs to him; and yet that it should be no discouragement to him to proceed in doing them all the service he was capable of.
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 (k); 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.