'Unbeliever' in the Bible

I (not the Lord) say to the rest of you: If a brother has a wife who is an unbeliever and she is willing to live with him, he must not abandon her.

And if a woman has a husband who is an unbeliever and he is willing to live with her, she must not abandon him.

If an unbeliever invites you to his house and you wish to go, eat whatever is set before you, raising no question on the grounds of conscience.

But if everyone is prophesying, when an unbeliever or an uneducated person comes in he will be convicted and examined by everything that's happening.