New Defender's Study Bible Notes
6:6 If they shall fall away. “If they shall fall away” from the true faith, having once fully understood it (“been enlightened,” having been made “partakers of the Holy Ghost,” etc.), then they can never return. “My Spirit shall not always strive with man” (Genesis 6:3). However, this seems to be a hypothetical situation—“if” they fall away. The question remains: can they fall away? The security of true believers in Christ is clearly taught in numerous other passages (John 10:27-29; Romans 8:35-39; Ephesians 1:11-14; I John 5:11-13; etc.), and all these prove that genuine Christians cannot fall away, for Christ Himself will keep them from it. Just as a babe, once born, cannot be unborn, so one who is “born again” into God’s family can never be not born-again. One is saved from hell when he truly accepts Christ, so he can never end up in hell; if he does, he certainly was not saved from it. The very concept of salvation would become meaningless. Nevertheless, the warning remains very clear. Many who appear to be true Christians and who may even believe themselves to be true Christians, can and do fall away and come to deny and oppose the faith they once thought they believed. They could not truly have believed it, however, or they would never have allowed doubts to come in and supersede the overwhelming evidences of its truth. “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” (I John 2:19).