APOSTASY (Gr., in classical Greek a defection or revolt from a military commander), a term generally employed to describe a complete renunciation of the Christian faith, or even an exchange of one form of it for another, especially if the motive be unworthy. In the first centuries of the Christian era, apostasy was most commonly induced by persecution, and was indicated by some outward act, such as offering incense to a heathen deity or blaspheming the name of Christ.  In the Roman Catholic Church the word is also applied to the renunciation of monastic vows (apostasis a monachatu), and to the abandonment of the clerical profession for the life of the world (apostasis a clericatu). Such defection was formerly often punished severely.
 The readmission of such apostates to the church was a matter that occasioned serious controversy. The emperor Julian's "Apostasy" is discussed under Julian.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)