21 lest, when I come again, my God will humble me among you, and I shall mourn for many who have sinned before and have not repented of the uncleanness, fornication, and lewdness which they have practiced.
The three sins of verse 21 refer to sexual sins.
21 lest, when I come again,
Paul’s second visit to Corinth was a humbling experience because the church rejected him (2 Co 2:1, 5). He is apprehensive that he will be humbled again on his upcoming visit to the city.
my God will humble me among you,
A humble servant grieves the fall of his people. In this case, Paul fears that the people he led to Christ will submerge into sexual sins. His humiliation had to do with his dealing with sexual sins in the church, among the people he led to Christ. He had a profound sense of responsibility for the church.
and I shall mourn for many who have sinned before
Some in Corinth sinned before Paul came the last time. The word “mourn” means to lament. In this case, Paul lamented the sinful state of the Corinthian church.
and have not repented of the uncleanness [impurity],
Many Corinthians had not repented of their sexual sins (1 Co 5:1-13). Some of them were unclean, that is, impure in their sexual lives (Ga 5:19; Eph 4:19; 5:3; Co 3:5; 1 Th 4:7). “Uncleanness” is the degradation of sex into promiscuity.
The sins of impurity, immorality, and licentiousness open the list of carnal sins in Galatians 5:19 (in a different order).
“Fornication” is a too narrow translation for its meaning. The idea is immorality of many types. It is the word from which we get the English term pornography (porneia), but it carries the idea of more than pornography, but sexual sin of any kind (1 Co 5:1; 6:13, 18; Eph 5:3; Co 3:5; 1 Th 4:3).
and lewdness [licentiousness, debauchery]
The Greek word for “lewdness” carries the idea of flagrant, public, sin (Ro 13:13; 1 Pe 4:3). It may include open drunkenness, carousing, and sexual promiscuity. The idea is that they defy public decency. This offends even the predominant culture where it resides. It is a manifestation of the flesh (Ga 5:19). Peter describes it as homosexuality (2 Pe 2:7).
which they have practiced.
The Corinthians previously practiced the sins of this verse. They did it as a habit, and now they are doing it again.
Our primary concern should be what God thinks of our ministry.
Most of us fear being humiliated by people but with Paul, he was more concerned about humiliation before God. When Christians follow the bankrupt world system, they are no different than non-Christians. The world today looks at the church with askance because what they profess, they do not practice. Moral collapse occurs after we flirt with Satan’s system.
Disunity causes moral laxity. Legalism and immorality are bedfellows (Jn 8:3-7).