Nonbeliever
ahd-5
noun.
One who does not believe or have faith, as in God or a philosophy.
Wiktionary, Creative Commons Attribution/Share-Alike License
noun.
a person who does not
believe
; especially regarding
religion
.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
noun.
someone who refuses to believe (as in a divinity)