Union with Christ: What It Is and Its Significance for Christian Growth

In the book of Romans, chapter 6, Paul reminds the believers in Rome about their union with Christ, saying, “If we have been united with him in a death like his, we shall certainly be united with him in a resurrection like his” (v. 5). But what exactly does Paul mean by this? How does he think this union with Christ impacts the Christian life in practical ways?

To many of us, these words from the apostle seem rather mysterious and hard to understand. So, it’s no wonder that the concept of this union has been a topic of much theological debate. Michael Gorman believes that “union with Christ” shows the way to a more faithful and “cruciform” (shaped like the cross, following the example of Christ’s self – sacrifice) Christian life. Ben Blackwell talks about “cruciformity” as a kind of mutual indwelling he terms “Christosis.” Others, following Tuomo Mannermaa, have explored connections with the Eastern Orthodox Church’s doctrine of “theosis.”

How can we evaluate these ideas based on the Scriptures? According to Paul, what does “union with Christ” really involve?

1. Union with Christ Assumes His Incarnation
   When Paul speaks of our union with Christ, he takes the incarnation for granted. This union is based on God sending his Son “in the likeness of sinful flesh and for sin” (Rom. 8:3). It’s evident that our union with Christ isn’t because we sought him out, but because he sought us and united with us. As Paul states elsewhere, “[Christ] loved me and gave himself for me” (Gal. 2:20).
2. Union with Christ Means Our Death and Resurrection with Him
   In Romans 6, Paul makes it clear that through Christ’s cross and resurrection, we are made new and our old selves are done away with. In Christ, our sin and guilt are overcome. Our union with Christ is complete; we don’t achieve or deepen it through inner meditation or moral efforts. Martin Luther once tried this approach and found that such attempts to escape “the world” were actually a form of self – centered love for the world. When his efforts failed, Luther encountered Christ and, as Bonhoeffer noted, the call to discipleship.
   Christ’s initial call to the disciples didn’t go as expected on their part, but Christ’s call remained effective. Despite Peter denying him (John 21:15–19), by the power of Christ’s cross and resurrection, the disciples could have said, like Paul, “I live, yet not I, but Christ lives in me” (Gal. 2:20, author’s translation). Their union with Christ was due to his love and power, not their own.
3. Union with Christ Isn’t Just an Inner, Mysterious Experience
   Christ’s self – giving love and power are communicated through an external message: first, the call to follow him, and then the apostolic preaching about his death and resurrection. Here, the Lutheran understanding of baptism and the Lord’s Supper (which I adhere to) gives us something to consider. Does my union with Christ depend on me reaching out to him for a spiritual gift? Or is it solely the result of his self – giving message to me? Can we share in Christ’s benefits without sharing in the crucified and risen Lord himself?
   We can see this communication of Christ through words in Romans 6. Paul indicates that union with Christ is fundamental to the Christian faith. To be baptized into Christ means being baptized into his death and experiencing, here and now, the new life of the age to come through his resurrection (vv. 3–4). In this chapter, Paul views our baptism as a way the gospel—and thus Christ himself—is communicated through the act of baptism with water.
   The “once – for – all” nature of baptism has a parallel in the Lord’s Supper. When Christ instituted the Supper, he gave himself and his saving death fully to those who partake of his body and blood (1 Cor. 10:16; 11:17–34).
4. Even Though Our Faith Varies, Union with Christ Is Complete
   There’s a paradox in our union with Christ. From the start of our faith, we are united with him without reservation, yet we also receive him again and again. Paul’s teachings reflect this. On one hand, he tells the Galatian believers, “As many of you as were baptized into Christ have put on Christ” (Gal. 3:27). On the other hand, he exhorts the Roman Christians, “Put on the Lord Jesus Christ, and make no provision for the flesh” (Rom. 13:14).
   The variable in the Christian life is our faith, which grasps the gospel message proclaimed, present in baptism, and in the Lord’s Supper. Faith is, of course, generated by the gospel message (Gal. 3:1–5; Rom. 10:14–17). But there’s another profound paradox: the message requires our response, our grasping of what Christ offers.
   The strength or weakness of our faith in receiving Christ’s promised word to us shapes our Christian lives. We are weak, but Christ is strong and wants to show his strength through our weakness. So, we need constant reminders of his complete self – communication to us through the cross and resurrection, which come through reading and preaching the Scriptures, through baptism, and through the Lord’s Supper.
5. In Union with Christ, the Believer and Christ Remain Distinct
   Paul says, “I have been crucified with Christ. It is no longer I who live, but Christ who lives in me” (Gal. 2:20). This passage shows that the union between Christ and the believer isn’t a blending but a communion where both parties remain distinct while sharing in what the other has. Luther used the marital imagery from Ephesians 5:29–32 when explaining the “freedom of a Christian” in this way. All our goodness comes from Christ. We have access to Christ’s benefits only when we “grasp” him by faith, just as he has already claimed us as his own (Phil. 3:12).
   So, if we talk about “Christosis” or “theosis” as part of salvation, we can’t think of it as a gradual absorption of divine power. Our new identity is found in Christ. For all eternity, we remain sinners redeemed by the Savior. If we use the term “theosis,” we should understand it as Luther did. In a marginal note on Galatians, he spoke of our “fideification.” In faith, the created being remains distinct from the Creator, and the sinner remains distinct from the Savior, even though they are joined through faith.
6. Union with Christ Doesn’t Mean Automatic Growth in Virtue
   Based on what has been discussed, it’s clear that union with Christ doesn’t involve a natural process of growing in spiritual understanding or virtue. Our union was already achieved through Christ’s victory over sin and death on the cross and in his resurrection. In what Luther called a “wonderful exchange,” our sin and death were overcome by Christ’s righteousness and life. Given this, we might wonder why sin still exists in us, why we have to fight against it, and why we need to pray “Forgive us our debts” (Matt. 6:12) every day throughout our earthly lives.
   Paul’s answer is straightforward. The old reality, the old human nature that is enslaved to sin like Adam’s, stays with us throughout our earthly journey (Rom. 7:14). This is the message not only in Romans 7 but also in Romans 6 and 8. We shouldn’t let sin rule in our mortal bodies or use our bodies to serve sin (6:12–13). We must “put to death” the actions of our old sinful selves (8:13). We live in the in – between time. The battle is won in Christ, but it still rages within us until our resurrection (6:5).
   This is the nature of the life of faith. Faith marks the presence of the new creation, created by the gospel message. This new creation, born of the word and faith, isn’t an abstract concept; it includes our bodily existence and obedience. This new person, living by faith, is constantly attacked by the world, our own fleshly desires, and the Devil. The “progress and joy” of the Christian life come from the faith that is centered in Christ, as we journey with him by faith alone (Phil. 1:25).
7. In Union with Christ, Suffering Is Necessary but Not Chosen
   From this point of view, we can assess the call to “cruciform living.” It’s clear from Paul’s letters that he sees suffering as an essential part of sharing in Christ. His words to the Philippians aren’t just for their situation: “It has been granted to you that for the sake of Christ you should not only believe in him but also suffer for his sake” (Phil. 1:29).
   The same idea is expressed regarding all believers in Romans 8:17: “We are ‘fellow heirs with Christ, provided we suffer with him in order that we may also be glorified with him.’” Christ’s sufferings are complete, yet his sufferings continue in those who belong to him.
   We’ve seen this paradox before in relation to the new life. Throughout Paul’s letters, suffering with and for Christ is emphasized more than serving Christ and showing his love. Serving and showing love come from our abundance and strength, used to help others. But suffering is passive. “Cruciformity,” which comes to all Christians in different degrees, is passive. If it’s suffering, it’s not something we choose for ourselves. It’s not a form of self – humiliation for the sake of moral improvement. While Jesus calls us to “take up [our] cross daily and follow [him]” (Luke 9:23), it’s “our cross,” the one God in Christ has given us. Much of the discussion about “cruciformity” leans towards moralism.
   Thinking of “cruciformity” as a moral obligation takes away the comfort and joy of the cross. Christ has already endured what we endure. Our sufferings are just an earthly extension of his completed sufferings. We can be confident that whatever we face, Christ has faced it before. He has not only gone before us but also taken our sufferings on himself and overcome them: “In the world you will have tribulation. But take heart; I have overcome the world” (John 16:33; cf. Matt. 12:15–21).
   We mustn’t forget that while the cross seems foolish and weak to the world, for believers, it’s the wisdom and power of God (1 Cor. 1:18). If we turn “cruciformity” into a moral duty, we risk losing what Johann Georg Hamann called the “great pleasure” of the cross, which can only be seen by the eyes of faith. Peter and the apostles rejoiced when they were considered worthy to suffer for Jesus’s name (Acts 5:41; cf. 1 Pet. 4:13–14).
   Love makes us recognize and grieve the sufferings of others and offer help, love, and care. But even this kind of love, like the love the Philippians showed Paul and that Paul called the Corinthians to show, isn’t suffering or “cruciformity” in the true, unchosen sense. We lose this true meaning at the risk of losing all comfort and joy in Christ. We are weak, but he is strong (2 Cor. 13:4–5).