1 Corinthians 7:10-14

10But to the married [believers] I give instructions—not I, but the Lord—that the wife is not to separate from her husband,

11(but even if she does leave him, let her remain single or else be reconciled to her husband) and that the husband should not leave his wife.

12To the rest I declare—I, not the Lord [since Jesus did not discuss this]—that if any [believing] brother has a wife who does not believe [in Christ], and she consents to live with him, he must not leave her.

13And if any [believing] woman has an unbelieving husband, and he consents to live with her, she must not leave him.

14For the unbelieving husband is sanctified [that is, he receives the blessings granted] through his [Christian] wife, and the unbelieving wife is sanctified through her believing husband. Otherwise your children would be [ceremonially] unclean, but as it is they are holy.