1 Corinthians 5:11

5:11 But now I am writing to you not to associate with anyone who calls himself a Christian who is sexually immoral, or greedy, or an idolater, or verbally abusive, or a drunkard, or a swindler. Do not even eat with such a person.

1 Corinthians 7:12

7:12 To the rest I say – I, not the Lord – if a brother has a wife who is not a believer and she is happy to live with him, he should not divorce her.

1 Corinthians 7:15

7:15 But if the unbeliever wants a divorce, let it take place. In these circumstances the brother or sister is not bound. God has called you in peace.