1 Corinthians 7:12-14

For all the others I say this (I am saying this, not the Lord): If a Christian man has a wife who is not a believer, and she is happy to live with him, he must not divorce her. And if a Christian woman has a husband who is not a believer, and he is happy to live with her, she must not divorce him. The husband who is not a believer is made holy through his believing wife. And the wife who is not a believer is made holy through her believing husband. If this were not true, your children would not be clean, but now your children are holy.