What is the relationship between 1 Corinthians and 2 Corinthians?
Second Corinthians is a follow-up to First Corinthians. The first letter addressed serious problems in the Corinthian church, and Paul had to be firm. The second letter defends his apostleship and encourages the believers who had apparently corrected those problems, showing the first letter accomplished its work.
Les explains that II Corinthians is a follow-up to the first letter, which had to deal with many problems in the Corinthian church. Those problems were like no other congregation under Paul's apostleship, so he had to get rather hard with them in I Corinthians. Now in II Corinthians he comes back in defense of his apostleship, but also to encourage these people who had seemingly corrected their problems. That change was an encouragement to the apostle, and he did not have to go personally because the message had come that his first letter had accomplished its work. They had dealt with the person involved in gross immorality, and he was evidently back in the fellowship.