1 Corinthians 7:12-14
12-14For the rest of you who are in mixed marriages—Christian married to non-Christian—we have no explicit command from the Master. So this is what you must do. If you are a man with a wife who is not a believer but who still wants to live with you, hold on to her. If you are a woman with a husband who is not a believer but he wants to live with you, hold on to him. The unbelieving husband shares to an extent in the holiness of his wife, and the unbelieving wife is likewise touched by the holiness of her husband. Otherwise, your children would be left out; as it is, they also are included in the spiritual purposes of God.
15-16On the other hand, if the unbelieving spouse walks out, you've got to let him or her go. You don't have to hold on desperately. God has called us to make the best of it, as peacefully as we can. You never know, wife: The way you handle this might bring your husband not only back to you but to God. You never know, husband: The way you handle this might bring your wife not only back to you but to God.