The expression union with Christ refers the believer’s solidarity or association with Christ, by the Holy Spirit and through faith, by virtue of which believers partake of his saving benefits.


This essay explores the meaning and significance of union with Christ in its various dimensions and concludes with a brief examination of two related questions: union with Christ as it relates to the unity of the history of salvation and to the believer’s justification.

Union with Christ: An Overview

While the expression “union with Christ” does not occur in the Bible, it describes the fundamental reality of the salvation revealed there, from its eternal design to its eschatological consummation.

Human beings are created in God’s image, to live in fellowship and communion (covenant) with God, trusting his promises and obeying his commands, loving and being loved. Sin, however, has destroyed this fellowship bond by rendering humanity both guilty and corrupt, alienated from God and deserving death. In response, God, as Savior, has undertaken to restore and perfect the life and communion lost. This saving purpose, intimated already in Genesis 3:14‒15, unfolds toward its fulfillment primarily through God’s ongoing dealings with Israel as his covenant people.

This covenant bond between God and Israel is expressed in various ways but perhaps most evocatively in the description of God himself as their “portion” (Psa. 73:26; 119:57; Jer. 10:16). Reciprocally—within the fellowship bond of the covenant—Israel is “the Lord’s portion” (Deut. 32:9; Isa. 53:12: “Therefore I will divide him [the messianic servant of the Lord] a portion with the many,” a prophetic reference to the church as Christ’s “portion”).

The climactic realization of this covenantal bond between the triune God and his people centers in union with Christ. The Emmanuel principle—“God with us”—that marks and controls covenant history from beginning to end comes to its consummate fulfilment in union with Christ.

This union finds its most prominent New Testament expression in the phrase “in Christ” / “in the Lord” (with slight variations), occurring frequently and almost exclusively in Paul’s letters (elsewhere, e.g., John 14:20; 15:4‒7; 1Jn. 2:28). Scholarly debate about the meaning of the phrase ranges from a purely instrumental understanding of the preposition “in,” to a local or atmospheric sense, and even the notion of an actual physical union between Christ and believers. In fact, Paul’s usage is varied, its scope best gauged by the contrast between Adam and Christ, as the second or last Adam (Rom. 5:12‒19; 1Cor. 15:20‒23, 45, 47). What each does is determinative for the destiny, respectively, for those “in him.”

For those “in Christ” this union or solidarity is all-encompassing; it extends from eternity to eternity. They are united to Christ not only in their present possession of salvation but also in its past, once-for-all accomplishment (e.g., Rom. 6:3‒7; 8:1; Gal. 2:20; Eph. 2:5‒6; Col. 3:1‒4), in their election “before the foundation of the world” (Eph. 1:4, 9), and in their still future glorification (Rom. 8:17; 1Cor. 15:22). ). Accordingly, we may categorize, being “in Christ” is either predestinarian, or past/redemptive-historical—the union involved in the once-for-all accomplishment of salvation (historia salutis)—or present, looking towards Christ’s return—union in the actual possession or application of salvation (ordo salutis). Another way of distinguishing these different aspects of union is “the eternal, the incarnational and the existential” (S. Ferguson).

In making such distinctions it is important to keep in mind that they refer to different aspects or phases of the same union, not to different unions. One ought not to think, as sometimes happens, in terms of two different unions in the application of salvation (the ordo salutis)—the one legal and representative, the other mystical and spiritual in the sense of being renovative, with the former seen as antecedent to the latter. To do that sacrifices the integral unity of the Bible’s outlook on the believer’s union with Christ, who can’t be “divided” (Calvin). In application there is only a single union, with distinguishable but inseparable legal and renovative aspects. At the same time, it is certainly no less important to maintain both aspects and to do so without equivocating on them—either by denying either aspect or blurring the distinction between them.

Present union, union in the actual appropriation of salvation, presupposes the continuation of the representative and substitutionary nature of union in both its predestinarian and past redemptive-historical aspects. To see Christ only as a representative for those in union with him, particularly as no more than a representative example and not also as their sin- and wrath-bearing substitute, seriously distorts biblical teaching about the work of Christ and the bond between him and his people.

Present union, then, may be considered as marked by four interrelated aspects: mystical, spiritual, vital, and indissoluble. Both mystical—a standard, classical designation—and spiritual are subject to misunderstanding. In view is not a mysticism of ecstatic experience at odds with or indifferent to reasoned understanding. Rather, union with Christ is a mystery in the New Testament sense of what has been hidden with God in his eternal purposes but now, finally, has been revealed in Christ, particularly in his death and resurrection (Rom. 16:25–26; Col. 1:26–27; 2:2).

Certainly, the full dimensions of this revealed mystery are beyond the believer’s comprehension. Involved here as much as in anything pertaining to salvation is the hallmark of all true theological understanding: the knowledge of Christ’s love “that surpasses knowledge,” the knowledge of what in its depths is beyond all human knowing (Eph. 3:18–19; cf. 1Cor. 2:9).

Ephesians 5:32 highlights the intimacy of this union (“a profound mystery,” NIV) by comparing it to the relationship between husband and wife. Elsewhere, other relational analogies bring out various facets of union: the foundation-cornerstone together with the other stones of a building (Eph. 2:19‒22; 1Pet. 2:4‒6); a vine and its branches (John 15:1‒7); the head and the other members of the human body (1Cor. 12:12‒27); the genetic tie between Adam and his posterity (Rom. 5:12‒19). The climactic comparison is to the unique union in being between Father, Son, and Spirit (John 17:20‒23).

Similarity is not identity, but especially this inner-Trinitarian analogy shows that the highest kind of union that exists for an image-bearing creature is the union of the believer with Christ as he has now been exalted. “The greatest mystery of creaturely relationships is the union of God’s people with Christ, and the mystery of it is attested by nothing less than this, that it is compared to the unity that exists in the Trinity” (John Murray).

Mystical union is spiritual, not in an immaterial, unsubstantial sense but because of the activity and indwelling of the Holy Spirit. To avoid misunderstanding, using Spiritual, capitalized, is advisable. Spiritual circumscribes the mystery and protects against confusing it with other kinds of union. As Spiritual, the union involved is neither ontological (like that between the persons of the Trinity), nor hypostatic (between Christ’s two natures), nor psycho-somatic (between body and soul in the human personality), nor somatic (between husband and wife), nor merely moral (unity in affection, understanding, purpose).

Spiritual union stems from the climactic and intimate relationship between Christ and the Holy Spirit. Because of his resurrection, the incarnate Christ (“the last Adam”) has been so transformed by the Spirit and is now in such complete possession of the Spirit that he has “become life-giving Spirit” (1Cor. 15:45) and as a result, “the Lord [= Christ] is the Spirit” (2Cor. 3:17). In view—without any compromise of the eternal ontological distinction between the second and third persons of the Trinity—is the functional or working identity of Christ as exalted and the Spirit, their oneness in the activity of giving resurrection-life and eschatological freedom.

In the life of the church and within believers, then, Christ and the Spirit are inseparable (cf. John 14:18), and mystical union, as it is Spiritual, is reciprocal. Not only are believers in Christ, he is “in them” (John 14:20; 17:23, 26; “… Christ in you, the hope of glory,” Col. 1:27). In Romans 8:9‒10 “in the Spirit,” “the Spirit in you,” “belonging to Christ” (equivalent to “in Christ”), and “Christ in you” are four facets of a single union. To have “his Spirit in your inner being” is for “Christ … [to] dwell in your hearts” (Eph. 3:16‒17).

As Spiritual, then, mystical union is also inherently vital. It is a life-union (cf. “… the law of the Spirit of life in Christ Jesus …,” Rom. 8:2 KJV/NKJ/NASB). Christ indwelling by the Spirit is the very life of the believer: “I no longer live, but Christ lives in me” (Gal. 2:20 NIV); “your life is hidden with Christ in God,” “Christ who is your life” (Col. 3:3, 4).

Finally, union with Christ is indissoluble. It is rooted in the unconditional and immutable decree of divine election “in him [Christ] before the foundation of the world” (Eph. 1:4). The salvation eternally purposed for believers “in Christ” is infallibly certain of reaching its eschatological consummation in their future resurrection-glorification ”in Christ” (Rom. 8:17; 1Cor. 15:22‒23). This hope, especially as it involves the enduring, unbreakable permanence of their union with Christ (Rom. 8:38‒39), finds quite striking expression in the Westminster Shorter Catechism (answer 37): “The souls of believers are at their death made perfect in holiness, and do immediately pass into glory; and their bodies, being still united to Christ, do rest in their graves till the resurrection” (emphasis added).

Related Issues

Two further matters may be addressed to round out this overview of union with Christ.

1. Union with Christ and the Unity of the History of Salvation.

Union with Christ is present only in the New Testament. Moreover, this union is not with just any Christ, with Christ in general. Rather, union is specifically with Christ as he has been exalted—with Christ who is now who he has become because of his incarnation and consequent obedient life, death, resurrection, ascension, and present heavenly session. As such, exalted, he is the source of all the benefits of the salvation he has accomplished as these benefits are applied to believers.

This raises the issue of salvation under the old covenant. How were sinners saved before Christ’s coming into history in “the fullness of time” (Gal. 4:4), before his death and resurrection, in other words, when union with him as exalted was not yet a reality? The answer lies in recognizing that union with Christ—a distinctive privilege of believers under the new covenant—is fellowship in covenant with God in its ultimate, eschatological form. As noted above, union with Christ is the consummate realization of the Emmanuel reality—God with us—that has governed covenant history from its beginning. Prior to the coming of Christ and the inauguration of the new covenant this bond of covenantal fellowship between God and his people already existed in its provisional and less than climactic form, beginning at the fall with God’s commitment to be their God and Savior (Gen. 3:15; cf. Exod. 6:7; Jer. 11:4 and many other passages).

Under the old covenant, then, salvation was by way of trusting God’s promise to be fulfilled in the future coming of the Messiah, Jesus, who “will save his people from their sins” (Matt. 1:21). So certain was the future fulfillment of that promise in Christ’s once-for-all accomplishment of salvation (historia salutis), that its basic benefits—both judicial and renovative—were applied (ordo salutis) to old covenant believers ahead of time, prospectively, prior to and in anticipation of the finished work of Christ in history.

So, in the New Testament we find that primary examples of justification by faith are old covenant believers—whether before or after the giving of the law at Sinai makes no difference—Abraham (Rom. 4; Gal. 3) and David (Rom. 4). Further, their justifying faith is hardly something they had of themselves or in their own strength but only because they had been regenerated by the Spirit. Both old and new covenant believers are “children of promise,” as both have been “born according to the Spirit” (Gal. 4:28–29).

There is, then, fundamental continuity in the application of salvation (the ordo salutis) between the old and new covenants. Under both, the benefits of Christ’s work are received within the bond of covenanted fellowship with the Triune God (cf. Westminster Confession of Faith 7.5–6; 11.6 for a helpful formulation of this state of affairs). The great, unprecedented difference, however, is this: New covenant believers are privileged to enjoy that fellowship bond in its consummate and most intimate form as union with Christ now exalted.

2. Union with Christ and Justification.

Especially since the Reformation, a perennially important issue, both in interpreting Scripture, especially Paul, and formulating church doctrine, has been the relationship between union with Christ and justification, between the participatory and the forensic aspects of salvation applied.

On the one hand, these are not merely alternate metaphors, as if one or the other may be ignored or otherwise dispensed with without sacrificing anything essential to and for salvation. But neither may union simply be coordinated as just one in a series of acts or facets in the application of salvation (the ordo salutis), with union viewed as following justification logically and causally as its result. Rather, as Calvin has already pointed the way, faithful to the New Testament, being united to Christ by faith through “the secret energy of the Spirit” (Institutes, 3.1.1) establishes the all-embracing bond within which the believer—without either separation or confusion of either benefit of the basic “two-fold grace” flowing from union—is both reckoned righteous and renewed in righteousness.

On the much mooted relationship of union and justification it seems difficult to improve on these words of Calvin, as incisive and as they are eloquent (Institutes, 3.11.10):

… I confess that we are deprived of this utterly incomparable good [righteousness] until Christ is made ours. Therefore, that joining together of Head and members, that indwelling of Christ in our hearts—in short, that mystical union—are accorded by us the highest degree of importance, so that Christ, having been made ours, makes us sharers with him in the gifts with which he has been endowed. We do not, therefore, contemplate him outside ourselves from afar in order that his righteousness may be imputed to us but because we put on Christ and are engrafted into his body—in short, because he deigns to make us one with him. For this reason, we glory that we have fellowship of righteousness with him.

Further Reading

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