'Unbeliever' in the Bible
The fool (the unbeliever and the ungodly) will no more be called noble, nor the crafty and greedy [for gain] said to be bountiful and princely.
If he pays no attention to them, tell the church. But if he doesn't pay attention even to the church, let him be like an unbeliever and a tax collector to you.
Then He said to Thomas, "Put your finger here and observe My hands. Reach out your hand and put it into My side. Don't be an unbeliever, but a believer."
The unbeliever does not receive the things of the Spirit of God, for they are foolishness to him. And he cannot understand them, because they are spiritually discerned.
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.
But if the unbeliever leaves, let him leave. A brother or a sister is not bound in such cases. God has called you to peace.
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 all are prophesying, and some unbeliever or uninformed person comes in, he is convicted by all and is judged by all.
What agreement does Christ have with Belial? Or what does a believer have in common with an unbeliever?
Now if anyone does not provide for his own relatives, and especially for his household, he has denied the faith and is worse than an unbeliever.