The doctrine of eternal security, connoted by the phrase “once saved, always saved”, teaches that it is impossible for the saved to lose their salvation. Jesus said, “I give eternal life to them, and they shall never perish; and no one shall snatch them out of My hand” and also “My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father’s hand” (John 10:28-29). We know that “the gifts and the calling of God are irrevocable” (Rom.11:29) and that “whom He predestined, these He also called; and whom He called, these He also justified; and whom He justified, these He also glorified” (Rom.8:30). We have also received a down payment in that all believers “were sealed in Him with the Holy Spirit of promise, who is given as a pledge of our inheritance, with a view to the redemption of God’s own possession, to the praise of His glory” (Eph.1:13-14). When God, who cannot lie, gives a pledge He always follows through with a full payment. The salvation of the saints is eternally secure. The phrase “once saved, always saved” refers to this biblical truth.
While “once saved, always saved” is widely embraced both by those who possess a genuine assurance of salvation as well as those who possess a false assurance of salvation, the doctrine of “perseverance of the saints” is far less likely to be embraced by those with a false assurance. This biblical doctrine not only implies eternal security but also teaches that those who are saved will not fall away but rather will remain in the faith. Perseverance conveys both the enduring of the believer and the abiding in Christ. Jesus said, “it is the one who has endured to the end who will be saved” and again “the one who endures to the end, he shall be saved” (Mat.10:22, 24:13). He also taught:
“I am the true vine, and My Father is the vinedresser. Every branch in Me that does not bear fruit, He takes away; and every branch that bears fruit, He prunes it, that it may bear more fruit. You are already clean because of the word which I have spoken to you. Abide in Me, and I in you. As the branch cannot bear fruit of itself, unless it abides in the vine, so neither can you, unless you abide in Me. I am the vine, you are the branches; he who abides in Me, and I in him, he bears much fruit; for apart from Me you can do nothing. If anyone does not abide in Me, he is thrown away as a branch, and dries up; and they gather them, and cast them into the fire, and they are burned. If you abide in Me, and My words abide in you, ask whatever you wish, and it shall be done for you. By this is My Father glorified, that you bear much fruit, and so prove to be My disciples” (John 15:1-8).
Enduring and abiding in Him, bearing supernatural fruit, living in joyful obedience that springs from Him, this is what proves salvation (Heb.3:6,12-14, 10:38-39; Gal.6:9). A person who considers himself a believer and yet is not daily dying to self, forsaking the world, obeying the Lord, and abiding in Him as evidenced by good fruit has just cause to question his salvation (Gal.5:19-24). The direction and deeds of a professed Christian evidence whether his faith is real or whether he is self-deceived (Jam.2:17-20). “He has now reconciled you in His fleshly body through death, in order to present you before Him holy and blameless and beyond reproach– if indeed you continue in the faith firmly established and steadfast” (Col.1:22-23). Continuance proves salvation because it is, without fail, the fruit of salvation.