1 Corinthians 7:12-14

But to the rest say I, not the Lord: If any brother hath an unbelieving wife, and she is content to dwell with him, let him not leave her. And the woman that hath an unbelieving husband, and he is content to dwell with her, let her not leave her husband. For the unbelieving husband is sanctified in the wife, and the unbelieving wife is sanctified in the brother: else were your children unclean; but now are they holy.