APOSTASY
apostasy, tergiversation
(noun) the act of abandoning a party for cause
apostasy, renunciation, defection
(noun) the state of having rejected your religious beliefs or your political party or a cause (often in favor of opposing beliefs or causes)
Source: WordNet® 3.1
Etymology
Noun
apostasy (countable and uncountable, plural apostasies)
The renunciation of a belief or set of beliefs.
Synonyms: backsliding, conversion, deconversion
Specifically, the renunciation of one's religion or faith.
Synonyms: defection, disaffection, estrangement
Source: Wiktionary
A*pos"ta*sy, n.; pl. Apostasies. Etym: [OE. apostasie, F. apostasie,
L. apostasia, fr. Gr. Off and Stand.]
Definition: 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.
Source: Webster’s Unabridged Dictionary 1913 Edition