'Unbelievers' in the Bible

but brother with brother doth go to be judged, and this before unbelievers!

If, therefore, the whole assembly may come together, to the same place, and all may speak with tongues, and there may come in unlearned or unbelievers, will they not say that ye are mad?

Become not yoked with others -- unbelievers, for what partaking is there to righteousness and lawlessness?