A deliberate defection or departure from a standing or faith. The Jews looked on Christians as apostates (Acts 21:21). There will come “the apostacy” from Christianity (2 Thess. 2:3). There is now a departing from the faith (1 Tim. 4:1). The Hebrews, who were on Christian ground, were in danger of departing from the living God (Heb. 3:12), and some from Christianity altogether, to return to the dead forms of Judaism (Heb. 6).