Union with Christ: What Is It, and What Does It Mean for Christian Growth?

In Romans 6 , Paul reminds believers in Rome of their union with Christ: “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). What does Paul mean? How does he understand being united with Christ to practically affect the Christian life?

To many of us, the apostle’s words seem mysterious and obscure. So it’s not surprising the question of this union has been taken up in theological discussion. Michael Gorman believes “union with Christ” points the way to more faithful and “cruciform” Christian living. Ben Blackwell says “cruciformity” entails a form of mutual indwelling he calls “Christosis.” Still others, following Tuomo Mannermaa , have made overtures to the Eastern Orthodox Church’s doctrine of “theosis.”

How do we evaluate these views before the Scriptures? According to Paul, what does “union with Christ” entail?

1. Union with Christ presupposes his incarnation.

When Paul says we’ve been united to Christ, he presupposes the incarnation. This union is predicated on God sending his Son “in the likeness of sinful flesh and for sin” (Rom. 8:3 ). It’s immediately clear our union isn’t based on our seeking Christ but on his seeking and becoming united with us. As Paul announces elsewhere, “[Christ] loved me and gave himself for me” (Gal. 2:20 ).

2. Union with Christ entails our death and resurrection with him.

Paul makes clear in Romans 6 that we were done away with—and made anew—in Christ’s cross and resurrection. In him, our sin and guilt were overcome. Christ’s union with us has effected our union with him without reserve and remainder. We don’t attain union—or deeper union—with Christ through inward meditation or moral endeavor. Luther attempted this route and discovered that such attempts to flee from “the world” are in reality radical love of this world and of self. When his attempts were shattered, Luther met Christ and, as Bonhoeffer observes , the call to discipleship.

Christ’s original call to the disciples ended in failure on their part—but not on Christ’s part. His call to come and follow him remained effective, despite Peter’s denying him (John 21:15–19 ). By the power of Christ’s cross and resurrection, they could have said with Paul, “I live, yet not I, but Christ lives in me” (Gal. 2:20 , author’s translation). They were united to Christ by his love and power, not by their own.

3. Union with Christ isn’t merely an inward, mysterious experience.

Christ’s self-giving love and power are communicated by an external word: first the word of his original call to follow and then the apostolic proclamation of his death and resurrection. Here the Lutheran understanding of baptism and the Lord’s Supper (to which I hold) offers something for us to reflect on: Does my union with Christ depend in part on my reaching up to him for a spiritual good he offers? Or is it purely the result of his self-giving word to me? Does sharing in Christ’s benefits take place apart from sharing in the crucified and risen Lord himself?

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We see this communication of Christ in word in Romans 6 , where Paul signals that union with Christ is elementary to Christian faith. To be baptized into Christ is to be baptized into his death and share here and now in the new life of the age to come through Christ’s resurrection (vv. 3–4). In this chapter, Paul understands our baptism as the communication of the gospel—and thus Christ himself—by means of the water in the baptismal act.

This “once for all” element of baptism has its counterpart in the Lord’s Supper. In Christ’s words of institution, he gives himself and his saving death without reserve to those who partake in his body and blood through the Supper (1 Cor. 10:16; 11:17–34 ).

4. Though our faith varies, union with Christ is complete.

This paradox of being united with Christ without reserve from the beginning of faith and yet receiving Christ again and again finds parallels in Paul’s instruction. On the one hand, Paul reminds 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 Christian living is faith that grasps the gospel word as it’s proclaimed, present in baptism, and present in the Lord’s Supper. To be sure, faith itself is worked by the word of the gospel (Gal. 3:1–5 ; Rom. 10:14–17 ). Yet in another profound paradox, the word calls for our response: our grasping and laying hold of what Christ gives.

The weakness or strength with which we grasp Christ in his word of promise to us determines the course of our Christian lives. We’re weak, but Christ is strong and wills to display his strength in our weakness. So we require constant reminders of his prior and complete communication of himself to us in his cross and resurrection through the reading and proclamation of the Scripture, through baptism, and through the 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 ). The passage shows us that the union of Christ and the believer isn’t a fusion but a communion in which both parties remain distinct yet share in all the other is. Luther makes use of the marital imagery of Ephesians 5:29–32 in precisely this way when explicating the “freedom of a Christian.” All our good lies outside us in Christ. We have Christ’s benefits only as we have Christ himself, “grasping” him by faith just as Christ has already laid hold of us and made us his own (Phil. 3:12 ).

Consequently, if we’re to speak of “Christosis” or “theosis” as an aspect of salvation, we may not think of it as a gradual infusion with divine power. Our new identity lies outside us in Christ. Into all eternity, we remain the sinner redeemed by the Savior. If we’re to speak of “theosis,” we may speak of it only with Luther, who in a marginal note on Galatians speaks of our “fideification.” In faith, the creature remains distinct from the Creator, the sinner distinct from the Savior, though they’re joined in the marriage of faith.

6. Union with Christ doesn’t entail growth in virtue.

In view of what I’ve just argued, it’s clear that union with Christ entails no natural process of growth in spiritual understanding or virtue. Our union has already been effected in Christ’s triumph over sin and death in his cross and resurrection. In a “wonderful exchange” (Luther’s phrasing ), our sin and death have been overcome by Christ’s righteousness and life. Given this reality, we may well ask why sin remains in us, why each one of us must battle sin, and why we must pray “Forgive us our debts” (Matt. 6:12 ) daily for the whole of our earthly lives.

Paul’s answer is simple. The old reality, the old human being subject to sin as a slave like Adam, remains with us through our entire earthly journey (Rom. 7:14 ). That’s Paul’s message not only in Romans 7 but in Romans 6 and 8 as well. We aren’t to allow sin to reign in our mortal bodies or serve sin with our members (6:12–13). We’re to “put to death” the “deeds of the body,” namely our old person who’s under the power of sin (8:13). We live between the times. The battle is over and won in Christ, but the battle still takes place in us until our resurrection (6:5).

This is the nature and form of the life of faith. The reality of faith marks the presence of the new creature, created by the word of the gospel, and this new creature, born of the word and faith, isn’t a ghost. It includes our bodily existence and obedience. This new person, who lives in faith, is constantly under assault from the world, the flesh, and the Devil. The “progress and joy” of Christian living comes on the path of the faith that’s present in Christ, with whom we travel by faith alone (Phil. 1:25 ).

7. In union with Christ, suffering is necessary but not chosen.

From this perspective, we can assess the call to “cruciform living.” It’s clear from Paul’s letters he regards suffering as a necessary dimension of sharing in Christ. His word to the Philippians can’t be limited to 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 thought appears in reference to 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.” The sufferings of Christ are complete, yet the sufferings of Christ continue in those who belong to him.

We’ve met this paradox already in relation to the new life. Throughout Paul’s letters, suffering with and for Christ has greater prominence than serving Christ and displaying his love. The latter arises from our abundance and strength used to help our neighbor. The former is passive. “Cruciformity” as it comes to us—and it comes to all Christians, albeit in varying measures —is passive. If it’s “suffering,” it’s not self-willed or self-chosen. It’s not a self-humiliation by which we delight in our own moral improvement. While it’s true Jesus calls us to “take up [our] cross daily and follow [him]” (Luke 9:23 ), it’s “our cross” we’re called to take up, the one God in Christ laid on us. Much of the discussion of “cruciformity” veers in the direction of moralism.

To conceive of “cruciformity” in terms of moral duty robs us of the comfort and joy of the cross. Christ has already borne for us what we bear. Our sufferings are merely the earthly extension of his sufferings, which are complete. We may then have confidence that whatever comes to us has come to Christ before. Not only has he gone before us but he’s also taken our sufferings on himself and overcome them already: “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 is foolishness and weakness to the world, for those who believe it’s the wisdom and power of God (1 Cor. 1:18 ). If we make “cruciformity” a moral obligation, we risk losing what Johann Georg Hamann has called the “great pleasure” of the cross, which is perceptible to the eyes of faith alone. Peter and the apostles rejoiced that they’d been found worthy to suffer for Jesus’s name (Acts 5:41 ; cf. 1 Pet. 4:13–14 ).

Love recognizes and laments the sufferings of others and offers all possible help, love, and concern. Yet even this love that shares in the sufferings of others—as the Philippians did with Paul, and as Paul calls the Corinthians to do—isn’t itself suffering or “cruciformity” in the proper, unchosen sense. We lose this proper sense only at the peril of losing all comfort and joy in Christ. We’re weak, but he’s strong (2 Cor. 13:4–5 ).

Mark Seifrid is a professor emeritus of exegetical theology at Concordia Seminary in St. Louis. His exegetical scholarship majors on the doctrine of justification. He’s the author of numerous books and scholarly articles, including his commentary on The Second Letter to the Corinthians and his NSBT volume, Christ, Our Righteousness: Paul’s Theology of Justification . He is married to Janice.