What is another word for "incredulousness"?

Roget's Thesaurus (1911) lists these synonyms for "incredulousness": agnostic, agnosticism, alien, aloof, antichristian, antichristianity, atheism, atheist, atheistic, belief, believe, bout, carnal, cynic, cynical, cynicism, deaf, dechristianize, deism, deist, deistical, devoutless, disbelief, disbelieve, disposed, distrust, distrustful, doubt, ear, earthly, faith, faithless, fort, freethinker, freethinking, gentile, giaour, godless, graceless, hard.