Having decided that Paul’s command was unreasonable, the Corinthians probably thought it best to ignore the command altogether. Thus, they continued to tolerate sexual immorality and other gross sins in their midst. Some of them even joined themselves to prostitutes (1 Corinthians 6:15–20) and participated in pagan temple meals (1 Corinthians 8:10; 1 Corinthians 10:19–22).
However, Paul had been referring to sinners in the church. The church members were not to keep company with people who professed to be believers while (like the man mentioned in 1 Corinthians 5:1–5) showing no signs of repentance.
Paul now repeats this command, stating that believers are not even to eat with such people (whether it be the Lord’s Supper or any other meal). The phrase not even to eat with such a one
is derived from the Septuagint version of Psalm 101:5b: A haughty look and an arrogant heart, with such a one I have not eaten.
The Corinthian believers should follow David’s example and strive to live blamelessly before the Lord.
In 2 Thessalonians 3:14–15 Paul also tells the church to have nothing to do with
a church member who disregards the apostles’ teachings. The goal is that this member will be ashamed.
By being excluded from fellowship with God’s church, he will get a foretaste of the eternal consequences of his sin. Yet, just as in 1 Corinthians 5:1–13, such a person is still called a brother.
It is because of the contradiction between this title and his actions that he is to be rebuked and avoided.
11 But now I am writing to you not to associate with anyone who bears the name of brother if he is guilty of sexual immorality or greed, or is an idolater, reviler, drunkard, or swindler not even to eat with such a one.