Disbeliever
Pronunciation : Dis`be*liev"er
Part of Speech : n.
Definition : Defn: One who disbelieves, or refuses belief; an unbeliever. Specifically, one who does not believe the Christian religion. I. Watts.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder