1 Corinthians 5:1

Church Discipline

5:1 It is actually reported that sexual immorality exists among you, the kind of immorality that is not permitted even among the Gentiles, so that someone is cohabiting with his father’s wife.

1 Corinthians 7:13

7:13 And if a woman has a husband who is not a believer and he is happy to live with her, she should not divorce him.