Apostasy Encyclopedia

Related: Apostasy of the Christian Profession; Eternal Security
What is Apostasy?

Apostasy is abandoning a belief once professed, especially in the context of renouncing the profession of faith in Christ. Apostasy is different from backsliding. A backslider is one who has truly believed on the Son of God, but has fallen into systematic failure, and is in need of restoration. An apostate is one who once made a profession of Christ, even partook of the outward blessings of Christianity, entertained the truth of it in their thoughts, yet never truly believed it, and ultimately turned away from it (1 Tim. 4:1). An apostate for a time is part of "the faith", but then abandons it, having never truly possessed "saving faith". For for such a person there is no possibility of restoration.

Misconceptions About Apostasy. Merely rejecting the gospel does not constitute apostasy. Hebrews 6 speaks of those who “were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost, and have tasted the good word of God, and the powers of the world to come” and yet remained unconverted. A person must have the full light of Christianity presented to them, and carry on with an outward profession of faith, then fall away from it in order to be an apostate. But if they do reject that testimony of the Spirit, the conclusion is solemn; “it is impossible… to renew them again unto repentance.” Incorrect use has been made of this scripture to teach that the believer’s security is conditional, and that it is possible, once saved, to be lost again. This is false, for it denies many other scriptures, such as John 10:27-29. Only an unbeliever can apostatize, because they never had saving faith to begin with. 
Apostasy and Apathy. A great deal of confusion comes in if we don’t understand what an apostate is, and what a backslider is. A backslider is one with real faith but who gets off the path and goes into sin. Their eternal destiny is secure, but their life may end up being a loss for Christ. Hebrews, 2 Peter, and Jude take up the subject of apostasy at length. Yet, is there nothing in those scriptures for the heart and conscience of those who do have genuine faith? Of course. Along with actual apostasy is the spirit of apostasy, or apathy. We are warned that the same spirit and principle that that leads apostates to fall away can affect those who are true believers, and produce lukewarmness in the soul.
Children of the Devil. Apostates in John’s Gospel are called “children of the devil” (John 8:37-47). It is very important to see that not every unsaved person is a child of the devil. All are children of Adam, in bondage to sin, children of disobedience, and children of wrath (Eph. 2:3), meaning that we are all born sinners, and heading down the road that leads to destruction. But a child of the devil is an apostate who has hardened himself against the truth, and thus given himself up to the service of Satan. In scripture we only find the Lord Himself identifying those who are the devil’s children, or those with apostolic authority, like Paul in Acts 13:10.