1.  apostasy(n = noun.state) defection, renunciation - the state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes);
is a kind of rejection

2.  apostasy(n = noun.act) tergiversation - the act of abandoning a party for cause;
is a kind of abandonment, desertion, forsaking

   An abandonment of what one has voluntarily professed; a total desertion of departure from one's faith, principles, or party; esp., the renunciation of a religious faith; as, Julian's apostasy from Christianity. [1913 Webster]

apostasy, n. (pl. -ies)
1 renunciation of a belief or faith, esp. religious.
2 abandonment of principles or of a party.
3 an instance of apostasy.

Etymology:
ME f. eccl.L f. NT Gk apostasia f. apostasis defection (as APO-, stat- stand)

N  tergiversation, change of mind, change of intention, change of purpose, afterthought, tergiversation, recantation, palinode, palinody, renunciation, abjuration, abjurement, defection, going over, apostasy, retraction, retractation, withdrawal, disavowal, revocation, revokement, reversal, repentance, redintegratio amoris, coquetry, vacillation, backsliding, volte-face, turn coat, turn tippet, rat, apostate, renegade, convert, pervert, proselyte, deserter, backslider, blackleg, crawfish, scab, mugwump, recidivist, time server, time pleaser, timist, Vicar of Bray, trimmer, ambidexter, weathercock, Janus, changeful, irresolute, ductile, slippery as an eel, trimming, ambidextrous, timeserving, coquetting, revocatory, reactionary, a change came o'er the spirit of my dream.

N  heterodoxy, error, false doctrine, heresy, schism, schismaticism, schismaticalness, recusancy, backsliding, apostasy, atheism, bigotry, fanaticism, iconoclasm, hyperorthodoxy, precisianism, bibliolatry, sabbatarianism, puritanism, anthropomorphism, idolatry, superstition, dissent, sectarism, sectarianism, noncomformity, secularism, syncretism, protestantism, Arianism, Adventism, Jansenism, Stundism, Erastianism, Calvinism, quakerism, methodism, anabaptism, Puseyism, tractarianism, ritualism, Origenism, Sabellianism, Socinianism, Deism, Theism, materialism, positivism, latitudinarianism High Church, Low Church, Broad Church, Free Church, ultramontanism, papism, papistry, monkery, papacy, Anglicanism, Catholicism, Romanism, popery, Scarlet Lady, Church of Rome, Greek Church, paganism, heathenism, ethicism, mythology, polytheism, ditheism, tritheism, dualism, heathendom, Judaism, Gentilism, Islamism, Islam, Mohammedanism, Babism, Sufiism, Neoplatonism, Turcism, Brahminism, Hinduism, Buddhism, Sabianism, Gnosticism, Hylotheism, Mormonism, Christian Science, heretic, apostate, antichrist, pagan, heathen, painim, paynim, giaour, gentile, pantheist, polytheist, idolator, schismatic, sectary, sectarian, sectarist, seceder, separatist, recusant, dissenter, nonconformist, nonjuror, bigot, fanatic, abdal, iconoclast, latitudinarian, Deist, Theist, Unitarian, positivist, materialist, Homoiousian, Homoousian, limitarian, theosophist, ubiquitarian, skeptic, Protestant, Huguenot, orthodox dissenter, Congregationalist, Independent, Episcopalian, Presbyterian, Lutheran, Calvinist, Methodist, Wesleyan, Ana, Baptist, Mormon, Latter-day Saint, Irvingite, Sandemanian, Glassite, Erastian, Sublapsarian, Supralapsarian, Gentoo, Antinomian, Swedenborgian, Adventist, Bible Christian, Bryanite, Brownian, Christian Scientist, Dunker, Ebionite, Eusebian, Faith Curer, Curist, Familist, Jovinianist, Libadist, Quaker, Restitutionist, Shaker, Stundist, Tunker, ultramontane, Anglican, Oxford School, tractarian, Puseyite, ritualist, Puritan, Catholic, Roman, Catholic, Romanist, papist, Jew, Hebrew, Rabbinist, Rabbist, Sadducee, Babist, Motazilite, Mohammedan, Mussulman, Moslem, Shiah, Sunni, Wahabi, Osmanli, Brahmin, Brahman, Parsee, Sufi, Buddhist, Magi, Gymnosophist, fire worshiper, Sabian, Gnostic, Rosicrucian, heterodox, heretical, unorthodox, unscriptural, uncanonical, antiscriptural, apocryphal, unchristian, antichristian, schismatic, recusant, iconoclastic, sectarian, dissenting, dissident, secular, (lay), pagan, heathen, heathenish, ethnic, ethnical, gentile, paynim, pantheistic, polytheistic, Judaical, Mohammedan, Brahminical, Buddhist, Romish, Protestant, bigoted superstitious, fanatical, idolatrous, visionary, slave to no sect, superstitione tollenda religio non tollitur.

N  improbity, dishonesty, dishonor, deviation from rectitude, disgrace, fraud, lying, bad faith, Punic faith, mala fides, Punica fides, infidelity, faithlessness, Judas kiss, betrayal, breach of promise, breach of trust, breach of faith, prodition, disloyalty, treason, high treason, apostasy, nonobservance, shabbiness, villainy, villany, baseness, abjection, debasement, turpitude, moral turpitude, laxity, trimming, shuffling, perfidy, perfidiousness, treachery, double dealing, unfairness, knavery, roguery, rascality, foul play, jobbing, jobbery, graft, bribery, venality, nepotism, corruption, job, shuffle, fishy transaction, barratry, sharp practice, heads I win tails you lose, mouth honor, dishonest, dishonorable, unconscientious, unscrupulous, fraudulent, knavish, disgraceful, wicked, false-hearted, disingenuous, unfair, one-sided, double, double- hearted, double-tongued, double-faced, timeserving, crooked, tortuous, insidious, Machiavelian, dark, slippery, fishy, perfidious, treacherous, perjured, infamous, arrant, foul, base, vile, ignominious, blackguard, contemptible, unrespectable, abject, mean, shabby, little, paltry, dirty, scurvy, scabby, sneaking, groveling, scrubby, rascally, pettifogging, beneath one, low-minded, low-thoughted, base-minded, undignified, indign, unbecoming, unbeseeming, unbefitting, derogatory, degrading, infra dignitatem, beneath one's dignity, ungentlemanly, ungentlemanlike, unknightly, unchivalric, unmanly, unhandsome, recreant, inglorious, corrupt, venal, debased, mongrel, faithless, of bad faith, false, unfaithful, disloyal, untrustworthy, trustless, trothless, lost to shame, dead to honor, barratrous, dishonestly, mala fide, like a thief in the night, by crooked paths, Int, O tempora!, O mores!, corruptissima respublica plurimae leges.