Synonyms and related words :
agnosticism, apostasy, backsliding, denial, desertion, disbelief, discredit, faithlessness, fall from grace, gentilism, heresy, impiety, impiousness, inability to believe, incredulity, infidelity, irreligion, irreverence, lapse, lapse from grace, minimifidianism, misbelief, nonbelief, nullifidianism, recidivism, recreancy, rejection, secularism, unbelief, unbelievingness, undutifulness