1 Corinthians 5:1-2 begins Paul’s rebuke of the Corinthian church, that one from among their congregation has had an affair with his own father’s wife. No one has confronted this sin; instead it has been ignored and tolerated. In their pride, the Corinthians have decided this sin is acceptable, and therefore not a sin. Paul confronts them that they ought to be grieved at the sin and remove the sinner from the assembly.

1 Corinthians 5:3-5 continues Paul’s rebuke. He tells the Corinthians that, even though he is not there with them in person, he is making a judgment against the sinful man as though he were there. A man has had an affair with father’s wife, and Paul is the only one calling it out as sin, despite not being in Corinth. Paul appeals to his authority as an Apostle, chosen by Jesus Christ, and tells the Corinthian believers that this unrepentant sinner has been cast out of the church. This is in the hope that the sinful man might repent and be restored to fellowship within the church and avoid loss of reward in the future judgment.

1 Corinthians 5:6-8 contains Paul’s explanation for why exiling a sinful believer is healthy. He turns his attention to the Corinthian congregation, making note that their pride has led them to diseased spirituality. By approving of the man’s sin, they have allowed a corrupting presence in the church which could ruin the spiritual health of everyone. Paul uses leaven and the Passover as illustrations of how sin is to be rejected and not tolerated. We must live in the truth, not in the welcomed presence of wickedness.

1 Corinthians 5:9-13 contains a clarification from Paul regarding who to associate with. He makes clear that it is right to disassociate from a believer who is openly sinning and will not repent. But this does not mean believers ought to shun the unsaved for their sin. Of course the unsaved sin. They are not in Christ; they cannot be expected to not sin or view sin as bad. We are called to preach the gospel to unbelievers, not to ignore them. But for believers in Christ who are sinning (for example, they covet, or worship an idol, or are hateful, or are a cheat, or a willing alcoholic) and do not want to stop sinning, do not want to change, then we should exile them from our lives. We should not be friends with Christians who want to go on sinning without repentance. God will judge nonbelievers. That is not our business. But wicked Christians will corrupt the church and should be sent out, in hopes that they repent of their sin and come back.