Synonyms and related words :
agnostic, ambiguous, capricious, chancy, changeable, creedless, dicey, disbelieving, doubting, equivocal, erratic, faithless, fickle, heretical, hesitant, hesitating, incalculable, incredulous, indecisive, indemonstrable, irreligious, irresolute, minimifidian, nonbelieving, nullifidian, polysemous, repudiative, skeptical, touch-and-go, unaccountable, unbelieving, uncertain, unconfident, unconfirmable, unconverted, undivinable, unforeseeable, unpersuaded, unpredictable, unprovable, unsure, unverifiable, variable, wavering, whimsical, without faith