The Collaborative International Dictionary of English v.0.48:

Misbelief \Mis`be*lief"\, n.
   Erroneous or false belief.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

48 Moby Thesaurus words for "misbelief":
   Albigensianism, Arianism, Catharism, Ebionitism, Erastianism,
   Gnosticism, Jovinianism, Lollardy, Manichaeanism, Manichaeism,
   Monophysism, Monophysitism, Pelagianism, Waldensianism, Wyclifism,
   airy nothing, antinomianism, autism, bubble, chimera, daydream,
   deception, deluded belief, delusion, dereism, dream, dream vision,
   dreamland, dreamworld, emanatism, error, fallacy, false belief,
   false doctrine, heresy, hylotheism, ignis fatuus, illusion,
   misconception, pantheism, pipe dream, self-deceit, self-deception,
   self-delusion, trick, trip, vapor, wrong impression