misbeliever

from WordNet (r) 3.0 (2006)

misbeliever
    n 1: a person who holds religious beliefs in conflict with the
         dogma of the Roman Catholic Church [syn: {heretic},
         {misbeliever}, {religious outcast}]

from The Collaborative International Dictionary of English v.0.48

Misbeliever \Mis`be*liev"er\, n.
   One who believes wrongly; one who holds a false religion.
   --Shak.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

27 Moby Thesaurus words for "misbeliever":
      Albigensian, Arian, Cathar, Donatist, Ebionite, Erastian, Gnostic,
      Jansenist, Lollard, Manichaean, Monophysite, Montanist, Pelagian,
      Sabellian, Waldensian, Wyclifite, antinomian, dissenter, dissident,
      emanationist, heretic, hylotheist, nonconformist, pantheist,
      schismatic, sectary, separatist

[email protected]