1 Corinthians 7:12-14

To the rest I say, which is not a saying of the Lord, if a brother has an unbelieving wife and she is content to live with him, he should not divorce her. And if a woman has a husband who is not a believer and he is content to live with her, she should not divorce him. For the unbelieving husband has been made holy by his believing wife. And the unbelieving wife has been made holy by her believing husband by virtue of his or her sacred union to a believer. Otherwise, the children from this union would be unclean, but in fact, they are holy.