Why did the four groups in Corinth cause Paul so much grief?
The four groups in Corinth caused Paul grief because they divided the church into competing factions—some following Christ, some Peter, some Apollos, and some Paul. This division reflected their carnality and failure to grow spiritually, producing dissension rather than unity.
Les explains that the Corinthian congregation was carnal and had not begun to grow and envelop the deeper things of Paul's teachings. Even though it was probably a small group, less than a hundred, there were four distinct divisions. Some claimed to follow Christ and His teachings; another group said they followed Peter; a third followed Apollos; and a fourth said they heard the gospel through Paul and would follow him. These four groups caused a lot of dissension and a lot of grief to the apostle and were part and parcel of their carnality—they just did not grow spiritually. Paul's first letter upbraided them for these problems, and by the time of the second letter, some things seem to have been corrected, though Paul still had to defend his apostleship.