unbeliever

noun

Etymology: From un- + believer, perhaps a corruption of earlier wanbeliever (“unbeliever”).

1. One who does not believe, particularly in a deity (used by believers to describe people who do not believe in the same deity or deities as themselves).

   “`Well, I suppose that we must try it,' I said; and the others assented in their various ways - Leo, as though it were the best joke in the world; Job, in respectful disgust; and Mahomed, with an invocation to the Prophet, and a comprehensive curse upon all unbelievers and their ways of thought and travel.”

   “I tried to persuade some of the men to come and save you, but they would not do it, saying: ‘Let the unbelievers kill one another if they wish. It is none of our affair, and if we go and interfere with Ali-ben-Ahmed’s plans we shall only stir up a fight with our own people.’”