Apostate
Webster's Dictionary [1]
(1): (a.) Pertaining to, or characterized by, apostasy; faithless to moral allegiance; renegade.
(2): (v. i.) To apostatize.
(3): (n.) One who has forsaken the faith, principles, or party, to which he before adhered; esp., one who has forsaken his religion for another; a pervert; a renegade.
(4): (n.) One who, after having received sacred orders, renounces his clerical profession.
Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]
(ἀποστάτης , a rebel, renegade), a term used, in its strict sense, by ecclesiastical writers, to designate one who has, either wholly or in part, left the true faith to embrace a false belief, or who has forsaken any holy profession to which he was bound by solemn vows. The term apostate is, in Church history, applied by way of emphasis to the Emperor Julian, who, though he had been nominally Christian when he came to the throne, renounced the Christian religion, and used every means in his power to reestablish paganism in the empire. (See Heretic).
The Nuttall Encyclopedia [3]
An epithet applied to the Emperor Julian, from his having, conscientiously however, abjured the Christian religion established by Constantine, in favour of paganism.
