Jonathan asked, "One question I have is how does union with Christ relate to the warnings in Scripture? Is it possible to have union with Christ in some sense and yet apostasize? I don't think so. Does the vine in John 15 have the same sense as union?"
Actually, there are three questions here, not simply one.
How does union with Christ relate to the warnings in Scripture?
Is it possible to have union with Christ in some sense and yet apostasize? I don't think so.
Does the vine in John 15 have the same sense as union?
Our union with Jesus Christ does not eliminate the need for warnings and admonitions nor does it mollify the urgency them. If we think biblically, it seems to me that our being in Jesus Christ places us under the proclamation of the gospel where the perpetual call--both admonishing and warning--ever and urgently beckons us to persevere in union with Christ Jesus. Thus, the apostle John says to us, "I write these things to you concerning those who are attempting to deceive you. And you, the anointing which you received from him persists in you and you have no need that someone teach you, but as his anointing teaches you concerning all things and is true and is not false, and just as it teaches you, persevere in him. And now, children, persevere in him in order that if he should appear we may obtain confidence and not be put to shame before him in his coming. If you know that he is righteous, you know that also everyone who does righteousness is born from him" (1 John 2:26-29; my translation).
So, biblically speaking, how does union with Christ relate to the warnings in Scripture? It seems to me that union with Christ calls for continual warnings and admonitions to be administered to us through the gospel. It also seems to me, biblically speaking, that warnings and admonitions are a primary means that God has assigned by which he preserves us in Christ Jesus.
Put starkly, then, not one of us who is in Christ Jesus ever finds ourselves outgrowing the need for the gospel's warnings and admonitions. Daily, we all need to hear the gospel, for the gospel warns and admonishes us that salvation is found nowhere else except in Christ Jesus.
I can do no better than to point you to The Race Set Before Us pages 209-212, where we discuss Acts 27 as we offer the illustration of how God's promise and God's warning function in Paul's announcement of God's promise by way of the Lord's angel that assured that no life would be lost that was aboard the ship (Acts 27:22-26) and in Paul's proclamation that reminded all on board the ship concerning God's promise how all the lives would be saved as he warned them, "If these men do not remain in the ship, you will not be saved" (Acts 27:31).
Being assured that we are in Christ and that being in Christ we shall be saved from the wrath to come is not contrary to being warned and admonished to remain in Christ in order that we might be saved from the wrath to come. This is the point that Jonathan Edwards so well grasped as he says, "'For though I preach the gospel, I have nothing to glory of, for necessity is laid upon me; yea, woe is unto me if I preach not the gospel.' What necessity was there upon the apostle to preach the gospel, though God had commanded him, for he was already converted, and was safe; and if he had neglected to preach the gospel, how could he have perished after he was converted? But yet this conditional proposition was still true; if he did not live a life of obedience to God, woe would be to him; woe to him, if he did not preach the gospel. The connexion still held. It is impossible a man should go any where else than to hell in a way of disobedience to God. And therefore he deemed it necessary for him to preach the gospel on that account, and on the same account he deemed it necessary to keep under his body, lest he should be a castaway."
I agree with you. No, it is not possible to have union with Christ and yet apostatize from Christ and perish. But, it seems to me, that if we allow this question to dominate and to direct our considerations of biblical warnings and admonitions, then we will be steered wrongly, and we will fail to acquire a biblical understanding of the function of the gospel's warnings and admonitions. This is the point that Tom Schreiner and I make throughout The Race Set Before Us and particularly emphasize on pages 194ff, when we talk about "Framing the right question."
My point is this, that when we attempt to understand biblical warnings and admonitions, many of us Christians fall prey to the preemptive question that leads to two wrong alternatives depending upon other beliefs that we already embrace. By answering the preemptive question first, Christians divide. Some answer "Yes" and others answer "No." Those who answer "yes" tend to receive biblical warnings and admonitions as perpetual reminders of how tenuous their salvation actual is. The trustworthiness of the gospel is brought into question. Those who answer "no" tend to engage in creative, amazing, and intricate gymnastic exegesis of biblical warnings and admonitions that spawns new problems. Some regard themselves exempted from the warnings and admonitions because they view themselves as secure in Christ. They need to hear 1 Corinthians 10:12. Others believe that in order for them to feel the force of the warnings and admonitions it is necessary to suspend all assurance that they are in Christ Jesus because to take the warnings and admonitions seriously means that they might be deluded to think that they are in Christ when in reality they may not be in him at all.
What is the preemtive question that we Christians allow to intrude and to mislead us? It is simply this: "Do the warnings and admonitions of Scripture teach us that it is possible for those who are in Christ Jesus to apostatize and to perish?" Observe carefully that I have called this the preemptive question. It is a valid question, but only in its proper order. The principal question that should guide us in how we receive biblical warnings and admonitions is quite different. The question we should be asking concerns the function of biblical warnings and admonitions not whether they call into question the sincerity of our trust in Christ nor the assurance that we are in Christ nor the firmness of God's promise that he will preserve us safely unto the Last Day. For further discussion of this, see TRSBU pages 195-200. If we ask the right question--the question concerning the purpose of warnings and admonitions--we will come to a right understanding of them, namely, that warnings and admonitions are God's means by which he preserves us safely in Christ Jesus.
Your question about John 15 reminds me concerning a large portion of text that Tom Schreiner and I removed from our manuscript to reduce its already too-large-size. Here is a portion of that segment that we eliminated from our book, lest our editor eliminate it for us.
As Christians read John 15, we generally fail to realize that Jesus’ principal purpose for the extended metaphor is not simply to portray the vital and living relationship between Jesus and his disciples, though this certainly becomes the emphasis. First and foremost, Jesus presents himself as the “true vine,” which is his metaphorical way to present himself as the “True Israel” (cf. Ps 80:8ff). Therefore, the branches in the vine represent God’s “new people,” his faithful people in contrast to apostate Israel. So, the faithlessness of Israel stands as a backdrop as Jesus admonishes, warns, and assures his “new people” concerning faithfulness to him. Yet, Jesus does not develop this replacement motif, but he does expand upon the imagery, for it suggests union, reciprocal indwelling, and fruitfulness, all apt metaphors to portray the profound relationship between Christ and his believers. It is analogous to the relationship in which the Son subordinates himself to his heavenly Father (John 15:4-5, 9-10).
John uses the verb “remain” to picture the reciprocal union of vitality between Christ, the vine, and believers, the branches. As the believer remains in vital union with Christ and bears fruit, so Christ remains in union with the believer, effectively nurturing the believer with the sap of eternal life. When Jesus says, “Remain in me, as I also remain in you.” (15:4; our translation), he makes it clear that the analogy between believer and branch is not to be pushed to an extreme, for a branch makes no effort to remain in a vine, but the believer must persevere in Jesus Christ. Jesus commands us to “remain” in him. As we have already noted, an imperative in a sentence such as this often bears a conditional sense. So, of the interpretive options, it is best to understand this command in a conditional sense, “If you remain in me, I also will remain in you.” Jesus reinforces this by adding a comparative conditional sentence, “Just as no branch can bear fruit on its own, unless it remains in the vine, so also neither can you unless you remain in me.” The point is clear. In the reciprocal union of Christ and believer, the vital life flows one way, for if the believer is severed from Christ, there is no vitality at all and certainly no fruit. Therefore, Jesus does not add “remaining” as a responsibility separate or distinct from “believing.” Rather, under the figure of a branch remaining joined with a vine, Jesus simply commands belief. Belief in him, that unites one to the source of eternal life, is persevering belief. It is not transitory or temporary, but persistent and productive.
According to Jesus, if a branch fails to bear fruit, God the Father severs it and casts it aside to await is destruction by fire (John 15:2, 6). A branch that fails to bear fruit and is therefore severed, of course, is one that fails to remain in Christ. But Jesus assures his disciples that they are ones the Father prunes with “the word I have spoken to you,” so that “you are already clean,” for Judas is no longer among them (cf. John 15:3 with 13:1-17, 30). Furthermore, Jesus assures the eleven, “You did not choose me, but I chose you and appointed you in order that you should go and bear fruit and that your fruit should remain” (15:16). Now it is important to point out that the promise we encounter in John 15:16 is different from those we have seen in Revelation 21:6-7 or in Matthew 10:22. Those two were conditional promises, the one in John 15:16 is unconditional.
How can we recognize that one is conditional and the other is unconditional? What is the essential difference between these biblical promises? We recognizes the difference by the way the Bible writers express them. Biblical writers express a conditional promise by using one of several ways to express a supposition or contingency. On the other hand, an unconditional promise of salvation is one in which God’s choice to save or his promise to preserve his children is not grounded upon any conditions that we must fulfill. Jesus announces to his disciples, “You did not choose me, but I chose you and appointed you in order that you should go and bear fruit. . . .” This means that Jesus did not base his choice of his disciples upon conditions that they had to meet. Elsewhere John speaks of God’s unconditional love when he says, “This is love: not that we loved God, but that he loved us and sent his Son as an atoning sacrifice for our sins” (1 John 4:10). John succinctly restates this, “We love because he first loved us” (1 John 4:19). These two verses make it clear that God did not love us because of something loveable in us; he did not set his affection upon us because of any condition we fulfilled, for we were unlovely sinful rebels against the Creator as is the whole world from which God chose his own (John 15:19). Furthermore, these two verses clarify that God’s love is the cause that moves us to love both him and one another. Likewise, in John 15, Jesus’ unconditional choice and promise functions as the basis for his exhortations and warnings. Immediately following the affirmation of election and the promise of preservation, Jesus admonishes his disciples, “Love each other!” (15:17).
So, within the same extended viticulture metaphor, Jesus warns his disciples that his Father severs unfruitful branches for burning (certainly an image of eternal perishing), yet Jesus assures his disciples that he elected them and ordained that they should bear fruit that endures (John 15:2, 16). And he also punctuates his extended admonition with conditional promises such as, “Remain in me, as I also remain in you” (15:4).
Therefore, my simple and short answer to your question--Does the vine in John 15 have the same sense as union?--is yes, it does.
My responses to Jonathan's questions may raise more questions. If so, please use the comments feature to pose your questions. Thank you.