Expositor's Bible Commentary Commentary 1 Corinthians 5:9

"I wrote unto you in my epistle to have no company with fornicators;" — 1 Corinthians 5:9 (ASV)

Though the letter here referred to could possibly be a reference to the preceding part of the present letter, it is more natural to conclude that Paul had written a previous letter that we do not possess. Paul now comments on a subject discussed in that former letter—that of not associating with sexually immoral people (those committing any type of sexual sins, including incest), a point the Corinthians had not fully understood. The social milieu in Corinth was notoriously immoral and if the Corinthians took the command in the previous letter too literally, as they seem to have done, they would have had to break contact with even some family members, business associates, and social acquaintances.