APOSTASY. (Gr. apostasia, "a falling away or defection from the faith").
While the Gr. word is used only twice in the NT (Acts 21:21; II Thess 2:3), it is found in the LXX several times, as in Josh 22:22, to express rebellion of the people from God, and in II Chr 29:19 of the casting away of the holy temple vessels.
Apostasy is possible only for nominal Christians. In the case of real believers, the Scripture declares that God either brings them back through suffering and chastisement (I Cor 11:29-30; I Cor 5:5) or removes them through death (I Cor 11:30). In the case of apostates, though He may allow them to remain, He withdraws from them all possibility of repentance and salvation (Heb 6:1-6; 10:26-31).
BACKSLIDING. A term used in the OT by God of Israel, particularly in Jeremiah, where the nation is spoken of as backsliding children (Jer 3:22), a backsliding daughter (Jer 31:22), and in Hosea where He calls Israel a backsliding heifer (Hos 4:16). Children who get into evil and a daughter who chooses a life of sin are familiar examples to people of all ages, and a backsliding heifer is a particularly expressive term to any farmer to portray stubbornness.
In the OT, backsliding speaks of a return or turn back to the old life of sin and the worship of false gods; in this day, a return to a former life of sin and spiritual idolatry, that is, to materialism and the worship of things rather than God. As used today in modern religious parlance, the term refers to the spiritual state of individual Christians.
The view that the backslider who though once saved has become lost again, fails to see that the Christian's standing must be distinguished from his state. Positionally, that is, as far as his standing is concerned, he is in Christ and eternally justified. He is safe against anything and anyone taking away his eternal life, since both Christ and the Father hold him in their hands (Jn 10:28-29). And yet the Christian's state is subject to change, since he is still imperfect and able either to progress or regress. The Christian's standing is spoken of in Col 2:10-13 as a perfection equal to Christ's; his state (I Cor 3:1-4; Rom 7), as one in danger of a constant degeneration into carnality. Backsliding invokes chastening from God (Heb 12:6; I Cor 11:32), and results in loss of rewards (II Cor 5:10; I Cor 3:15), loss of fellowship (I Jn 1:7), removal from a place of usefulness (I Cor 5:5; 11:30), and sometimes even calls for removal from this life by death (I Cor 11:30).