1 Corinthians 7:14-16
For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband…
The Christian wife lays her heathen husband upon the altar of God; and in all her intercourse with him acts as God's servant, striving ever to accomplish His purposes. Therefore, whatever the husband may be in himself, he, in the subjective world of her thought and life, is a holy object; and her treatment of him is a sacrifice to God. Such intercourse cannot defile. Therefore his heathenism is not in itself a reason for separation.
Parallel VersesKJV: For the unbelieving husband is sanctified by the wife, and the unbelieving wife is sanctified by the husband: else were your children unclean; but now are they holy.