“That whoever believes in him may have eternal life.”
“John 3:15 states that whoever believes in Jesus Christ will “have eternal life.” If you believe in Christ today and have eternal life, but lose it tomorrow, then it was never “eternal” at all. Hence if you lose your salvation, the promises of eternal life in the Bible would be in error.” 1
There are two flaws in this reasoning:
The problem with using this as a proof text for OSAS is the assumption that ‘eternal life’ is the inalienable property of the believer. Such is not the case: the same apostle who recorded these words of Jesus also wrote that “God gave us eternal life, and this life is in his Son. Whoever has the Son has life; whoever does not have the Son of God does not have life.” (1 John 5:11-12; cf. John 1:4; 5:26; 6:35; 11:25; 14:6; Col. 3:3-4; 2 Pet. 1:4; 1 John 1:2) This makes it clear that eternal life is the inalienable property of Jesus Christ, not the believer; the believer can only share in this blessing as long as he is in Christ. It should also be noted that John 3:15 does not say anything about whether it is possible to get ‘out of Christ’ and thus forfeit eternal life (which means that the verse by itself does not come close to proving OSAS), but later in the same gospel, Jesus makes it clear that it is, in fact, possible for a branch to stop abiding in Christ (John 15:1-6).
The second flaw is in the OSAS proponent’s view of eternal life. They said, “If you believe in Christ today and have eternal life, but lose it tomorrow, then it was never “eternal” at all” (emphasis added). But this does not follow.
Think of it like this: Willy Wonka gives Charlie an everlasting gobstopper. In the end, Charlie gives it back to Willy Wonka, thereby giving up possession of the everlasting gobstopper. In this scenario, has the quality of the gobstopper changed? No; Charlie has simply forsaken his possession of it. It makes no sense whatsoever to think that because Charlie gave up possession of the everlasting gobstopper, that it was never an everlasting gobstopper to begin with.
And so it is with eternal life – if someone were to lose it, it would in no way affect the eternal quality of the life. It would just mean that such a person is no longer is in possession of eternal life. Whether we choose to accept the gift of eternal life or not has no bearing on the quality of the life that is offered. Eternal life is in Christ Jesus, and it will remain eternal regardless of whether we possess it or not.
John 3:15 by itself does not prove OSAS, as it simply promises that those who believe will have eternal life. From this it follows that those who don’t believe (regardless of whether they once believed) will not have eternal life. Example: think of the statement, ‘He who breathes will have life.’ The phrase ‘he who breathes,’ carries the notion of a continual action, and not a ‘one-off’ action, performed sometime in the past. The life that results from breathing is a consequence of a present tense action.
Likewise, the eternal life that is offered in John 3:15 is not promised to those who once believed (sometime in the past), but to those who believe (i.e., those who believe now, in the present).