'Unbelieving' in the Bible

But as to the rest, I say, not the Lord, If any brother have an unbelieving wife, and she consent to dwell with him, let him not leave her.

And a woman who has an unbelieving husband, and he consents 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; since otherwise indeed your children are unclean, but now they are holy.