Synonyms of disbelievers

2 Syllables
atheist, heathen, scoffer, pagan, doubter, cynic
3 Syllables
agnostic, profaner, questioner, dissenter, heretic, freethinker, infidel, nihilist, pessimist
4 Syllables
unbeliever, misbeliever, misanthrope, materialist, rationalist, apostate