"They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us." (1 John 2:19)
One of the most hurtful experiences in the life of a Bible-believing fellowship is when an ostensibly Christian leader, teacher, or pastor decides to abandon his faith and even to teach against it. This sort of thing does happen all too often, and it obviously raises difficult questions.
Can a true believer, a teacher of the Word, a soul-winner, actually lose his salvation? Can a born-again Christian go back and be unborn? Can one who has received everlasting life through faith in Christ not really have eternal life?
The answer to this vexing question is apparently in our text verse above. When such people, who once seemed to be genuine Christians become apostates, denouncing the truth they once taught, it is because "they were not of us" at all, no matter what they professed at one time.
This fact implies a sober warning. When professing Christians fall away, assuming they have truly understood the facts and evidences of the Christian faith, it is impossible "to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put Him to an open shame" (Hebrews 6:6).
How important it is, therefore, for all professing believers to "give diligence to make your calling and election sure" (2 Peter 1:10). We must be "rooted and built up in him" (Colossians 2:7), "ready always to give an answer to every man that asketh you a reason of the hope that is in you with meekness and fear" (1 Peter 3:15). HMM