Apostasy(n.) A total desertion or departure from one's faith, principles, or party; as, Julian's apostasy from Christianity; An abandonment of what one has voluntarily professed;
Thesaurus Entries
Evangelicalism, Protestantism, Reform, Zwinglianism, about-face, accommodation, adaptation, adjustment, agreement to disagree, alienation, alteration, amelioration, atheism, backsliding, betrayal, betterment, bolt, break, breakaway, change, change of heart, changeableness, constructive change, continuity, conversion, counter-culture, crossing-over, defection, degeneration, degenerative change, dereliction, deserter, desertion, deterioration, deviation, difference, disaccord, disagreement, disapprobation, disapproval, discontinuity, disloyalty, disparity, dissatisfaction, dissension, dissent, dissentience, dissidence, divergence, diversification, diversion, diversity, dropping out, faithlessness, fall from grace, falseness, fitting, flip-flop, going over, gradual change, impiety, impiousness, improvement, irreligion, irreverence, lapse, lapse from grace, melioration, minority opinion, mitigation, modification, modulation, new theology, nonagreement, nonassent, nonconcurrence, nonconformity, nonconsent, opposition, overthrow, perfidy, qualification, radical change, ratting, re-creation, realignment, recidivation, recidivism, recreancy, recusance, recusancy, redesign, reform, reformation, rejection, remaking, renewal, renunciation, repudiation, reshaping, restructuring, reversal, revival, revivification, revolution, schism, secession, shift, sudden change, switch, tergiversation, total change, transition, treacherousness, treason, turn, turnabout, turning traitor, underground, undutifulness, upheaval, variance, variation, variety, violent change, walkout, withdrawal, worsening