This is JESUS' own words:
John 15:1 “I am the true vine, and my Father is the gardener. 2 He cuts off every branch in me that bears no fruit, while every branch that does bear fruit he prunes so that it will be even more fruitful. 3 You are already clean because of the word I have spoken to you. 4 Remain in me, as I also remain in you. No branch can bear fruit by itself; it must remain in the vine. Neither can you bear fruit unless you remain in me.
5 “I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing. 6 If you do not remain in me, you are like a branch that is thrown away and withers; such branches are picked up, thrown into the fire and burned.
It doesn't get any clearer than that. Jesus is warning us here. If OSAS was true, He would have never said it to us in the first place.
In John 15:2-6, the
branches that bear fruit and remain are genuine believers (like the remaining 11 disciples). The self-attached branches that
bear no fruit and do not remain are not genuine believers (like Judas Iscariot). In John 15:2, Jesus mentions
branches that bear no fruit and
branches that bear fruit but Jesus says
nothing about branches that bear fruit but then later stop bearing fruit.
Greek scholar AT Robertson points out that there are
two kinds of connections with Christ as the vine (the merely cosmic which bears no fruit, the spiritual and vital which bears fruit). Probably (Bernard) Jesus here refers to Judas.
John 15 - Robertson's Word Pictures in the New Testament - Bible Commentaries - StudyLight.org
When Jesus spoke these words in John 15, how many people at that time,
prior to Him being glorified, had received the Holy Spirit and were baptized by one Spirit into one body? - "the body of Christ?" (1 Corinthians 12:13) --
NONE.
John 7:38 - He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water. 39
But this He spoke concerning the Spirit, whom those believing in Him would receive; for the Holy Spirit was not yet given, because Jesus was not yet glorified.
So "in me" is part of the metaphor of the vine (in the vine) and not in the body of Christ under the new covenant which was not yet fully established. Without that vital union with Christ, there can be no spiritual life and no productivity. Those who profess to know Christ but whose relationship to Him is self-attached, Christ neither saved them, nor sustains them. Eventually, the dead self-attached fruitless branches are cut off.
The Greek word for “abide” is "meno" which means to remain, tarry, not to depart, continue to be present. Abiding in Christ is not a special level of Christian experience that is only available to a few, elite Christians, but is the position of all true believers. 1 John 4:13 - By this we know that we abide in Him, and He in us, because He has given us of His Spirit.. 15 Whoever confesses that Jesus is the Son of God, God abides in him, and he in God.
Also:
Romans 11:17 If some of the branches have been broken off, and you, though a wild olive shoot, have been grafted in among the others and now share in the nourishing sap from the olive root, 18 do not consider yourself to be superior to those other branches. If you do, consider this: You do not support the root, but the root supports you. 19 You will say then, “Branches were broken off so that I could be grafted in.” 20 Granted. But they were broken off because of unbelief, and you stand by faith. Do not be arrogant, but tremble. 21 For if God did not spare the natural branches, he will not spare you either.
22 Consider therefore the kindness and sternness of God: sternness to those who fell, but kindness to you, provided that you continue in his kindness. Otherwise, you also will be cut off.
Anyone grafted into the vine is saved. So, there is that responsibility to God to remain abiding in Him as He is the root that supports us. Those that were not spared however cannot be considered "never saved" because they were actually grafted in the vine - at one time abiding in Christ.
How about a little context. The Jews were in the olive tree to begin with because they were the
"natural branches" and not because they were all saved. Because of their unbelief and hard hearts God removed His gracious hand from them as a people overall and broke them off from His goodness (but only for a time after which they will be restored - Romans 11:24-26).
We Gentiles have now been grafted into God's goodness and are the recipients of His blessings. Paul's warning is that we should not become arrogant because we might lose the goodness and blessings of God just like the Jews lost the goodness and blessings of God.
Professing Christians who are Gentiles are corporately in outward covenant with Christ so, it would appear that Romans 11 is speaking about the question of collective ecclesiology and not individual soteriology. I see the warning to this collective body, which is corporately joined to Christ and is in a covenant relationship, but how could this mean that every individual in it is in saving union with Christ? Hence the "cut off."
Union with Christ applies to the elect, and only for the elect are,
"the gifts and the call of God are irrevocable." (verse 29) But since non-elect covenant members are mixed in, Christ clearly appears to have non-elect branches, like Judas Iscariot (John 15:1-8) and while they may be joined outwardly in covenant with Christ, since they have professed faith in Jesus, the faith of some of them is spurious because they were never truly saved to begin with, even though they were among genuine believers. (1 John 2:19).
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