Apostatize \A*pos"ta*tize\, v. i. [imp. & p. p. {Apostatized}; p. pr. & vb. n. {Apostatizing}.] [LL. apostatizare.] To renounce totally a religious belief once professed; to forsake one's church, the faith or principles once held, or the party to which one has previously adhered. [1913 Webster] He apostatized from his old faith in facts, took to believing in ?emblances. --Carlyle. [1913 Webster]