V. RESULTS OF REASONING
[Nouns] incredulousness, incredulity; skepticism, pyrrhonism; want of faith (irreligion) [more].
suspiciousness; scrupulosity; suspicion (unbelief) [more].
unbeliever, skeptic; misbeliever; pyrrhonist; heretic (heterodox) [more].
[Verbs] be incredulous; distrust (disbelieve) [more]; refuse to believe; shut one's eyes to, shut one's ears to; turn a deaf ear to; hold aloof, ignore, nullis jurare in verba magistri.
hard to believe.