Books Christology Soteriology

Creation, Incarnation, and Union with Christ






I have benefited significantly from previous work by Robert Letham, so I am happy to be reading his new work, Union with Christ: in Scripture, History and Theology. I have chosen to work through the book because I concur with Letham that “union with Christ is right at the center of the Christian doctrine of salvation,” and that “the whole of our relationship with God can be summed up in such terms” (1). The importance of this doctrine is evident in the writings of the apostles Paul (Eph 1:3-14), John (Jn 14:16ff., 17:21ff.), and Peter (1 Pet 1:3-4) (4-5). Soteriologically, we find it particularly connected with the doctrines of justification (Rom 3:21ff., 4:25, 5:12-21), sanctification (Rom 6:1ff.), and resurrection (1 Cor 15) (5-6). Despite this biblical reality, Letham has written this book because he has observed that:

 Today not much is said about union with Christ from the pulpit, and until recently little was written about it. (2)

A summary of Letham’s presentation in chapters 1 and 2


The first chapter addresses the relationship between God’s creation of humankind in God’s image and union with Christ, the latter resting on the basis of the former (9). The Trinitarian nature of God is evident in Scripture’s creation account, where we discover God to be a relational being who creates the heavens and the earth (Gen 1:1), hovers over the waters by his Spirit (1:2), and brings things into being by his fiat speech acts (1:3) (11). God is spoken of in terms both plural (Gen 1:26) and singular (1:27), and humankind is also plural (male and female) and singular (12).

Christ is the mediator of creation (Jn 1:1-4; Col 1:13, 16-17; Heb 1:2-3). In him all of creation is held together, he governs world affairs (Rev 5), and he is the goal of all of creation (Heb 1:2-3; Eph 1:10). But it is humankind that is created in the image of God, which is Christ (2 Cor 4:4; Col 1:15). And only in Christ, the second Adam (1 Cor 15:45-49), are fallen humans renewed in that image in knowledge, righteousness, and holiness (Eph 4:24; Col 3:10).

Having been created in God’s image, humans were made for communion with God and “to rule God’s creation on his behalf” (15 – see Gen 1; Ps 8:3-8). The Creator-creature distinction is clear in this relationship, but so is the inherent compatibility between them (15-16). But the fall of Adam and Eve into sin disrupted their relationships with the rest of creation, with one another,  and with God. The good news is that Christ, having been made for a little while lower than the angels (Ps 8), is now seated at the right hand of God, fulfilling God’s purpose for the human race at creation; and he is bringing all who are in union with him to share with him in the rule over the renovated cosmos (17).


Letham reviews the biblical testimony to the incarnation of the Son of God, and the creedal witness (Niceno-Constantinopolitan, Heidelberg Catechism 16) concerning its necessity for our salvation (19-21). He is careful to insist that in joining himself to humanity, the Son remained God, and that it is God who is the active agent. So the subject of the circumstances of the life of Jesus is “the One who created all things and upholds the universe; it is the Son through whom God has spoken his final culminating word of salvation (Heb 2:5-18; cf. 1:1-14), who prayed to the Father with loud cries and tears (4:14-5:10) (22).

In an excellent excursus, Letham traces the development of Christological thought to the second Council of Constantinople (A.D. 553). He describes (23-35):

  • the crisis arising from conflict between Nestorius (who spoke uncertainly of the unity of the person of the incarnate Word) and Cyril of Alexandria, and its resolution at the Council of Ephesus (431);
  • Eutyches’ opposition to Cyrilline Christology (with so strong an emphasis on the unity of the person that the distinctness of the two natures was blurred);
  • the church’s Definition at Chalcedon (451), in which the unity of the person and the distinctness of the natures was clearly affirmed;
  • the ongoing problem of the Monophysites, “who were accustomed to think of nature as synonymous with what we would now call person and for whom Chalcedon seemed an unwarranted capitulation to Nestorius” (28). Pope Leo and his legates to the Council failed to appreciate that the Greeks were then using phusis and hypostasis interchangeably, and it was not until a century later that Emperor Justinian I distinguished the two terms clearly. Letham helpfully notes the importance of this for our understanding of the anathema against those who talk of two natures of the Lord before the union but only one afterward. This was aimed at Eutyches, not at Cyril’s position
  • the unfinished business left on the table by Chalcedon:
    • it did not adequately address some of the Cyrillian concerns for the unity of Christ, because it “could be taken to mean that human attributes must be predicated only of the human nature, and the divine of the divine” (28)
    • it “left the concept of the hypostatic union unclear,” in that it did not specify, for instance, “who exactly it was who had suffered and been crucified,” and it did not say “that the deification of man began in the union of Christ’s humanity with his divine,” which was important to Cyril’s supporters (28). Because Chalcedon made no mention of the hypostatic union and refused to include the confession “out of two,” Chalcedon thus “satisfied the West but not the East” (28).
  • the fundamental disagreement between the Monophysites and the Chalcedonians. The former “insisted on the absolute unity of the person of Christ and his continuity with the preincarnate Logos,” but the Chalcedonians “were fearful of minimizing the humanity of Christ and could never accept that Christ’s manhood was merely a ‘state’ of the Logos” (30);
  • the contribution made by Leontius of Byzantium with his idea that Christ’s humanity was enhypostatos, so that his human nature “subsists in the hypostasis [roughly “person”] of the divine nature” (30). In this proposal, all operations of both natures are attributed to the person of the divine Word.
  • the “foundations for a coherent doctrine of union with Christ and deification” which were contributed by Leontius of Jerusalem, between 532 and 536. “Because Christ’s humanity has divine life hypostatically, we can—in union with Christ—receive divine life by grace and participation” (32).
  • Emperor Justinian I’s establishment of the distinction between hypostasis and nature, which “clarified Chalcedon (the union of two natures in one hypostasis) by identifying the hypostasis of Christ as the preexistent hypostasis of the divine Word,” so that “the person of Jesus Christ is the eternal Son of God, now incarnate” (33). In “The Edict of the True Faith” (551), “in contrast to Chalcedon, which used hypostasis to refer to the outcome of the two natures coming together into one Christ, Justinian used it of the preexistent Logos” (34). Justinian thus “shared with the Monophysites the principle that Jesus Christ is the divine Logos,” but he greatly clarified things by distinguishing “nature and hypostasis according to the Trinitarian distinction of the Cappadocians” (34). The problem of the Monophysites was that they “used nature as a synonym for hypostasis when talking of the particular but used nature as a synonym for essence (being) when talking of the universal” (34).
  •  the logical clarification of Chalcedon’s Definition which was attained in the Canons of Constantinople II (553), drawing upon intervening development (35).

Beautifully, Letham describes how the central covenant promise of covenant fellowship with God is fulfilled in Christ. He proposes that the Christian faith can be summed up as a series of unions: “the union of the three persons of the Trinity, the union of the Son of God with our human nature, the union of Christ with his church, the union established by the Holy Spirit with us as he indwells us,” in each of which real union exists between the members, without them being absorbed into one another (37). As a final point, Letham affirms the perpetual humanity (body and soul) of Christ. As our Savior, Christ is the head of his church “and will continue to be so without end.” But also, “as the Mediator of creation, he has assumed the full authority given to man in creation, lost and misused by Adam but now fulfilled in his ministry as the second Adam” (39).        

My reflections


Letham writes clearly, and I am impressed with the skilful way in which he has laid out conclusions drawn from extensive research. His statement regarding the Son’s work in creation raised no questions in my mind. I found his analysis of the development of the church’s understanding of the incarnation particularly helpful. In his discussion of the perpetual humanity of Christ, Letham has a good discussion of possible problems in Calvin’s thought in this regard (39-40). In my own reading of Calvin, I have been troubled occasionally by what looked to me like an unhealthy drifting into Nestorianism. Letham gives Calvin the benefit of the doubt in connection with some of his exegesis but he does well to warn us of danger in some of Calvin’s writings.

Points that I am pondering

1. The implications of the incarnation for our deification

In my own Christological development to date, I have tended to stress the union of the preincarnate Word with a human nature, in such a way that he became genuinely human in addition to remaining divine. But I have generally thought of this as the nature of a human being, as mine is. As a result, I have been leery of some Roman Catholic documents and of statements by Catholic theologians who speak of the incarnation as a union of the Word with human nature generically, in a way that seemed to unite him with the whole of humanity. My nervousness about this concept also made the Orthodox emphasis on deification somewhat alien to my own Christology and soteriology. At times, it has seemed to me that I was hearing a soteriology in which the Word accomplished salvation by means of the incarnation, diminishing the necessity of Christ’s atoning death.

In retrospect of reading Letham’s work, however, I will be approaching such statements in Roman Catholic and Eastern theology with a new openness. I have a hunch that I may have been misconstruing their intent, and that my own ways of thinking and speaking about the incarnation may need revision.

Letham observes that “the East claims that the flesh or humanity of Christ was deified by participation in the Son of God” (32). He finds biblical evidence for this, “among other places,” in the angel’s words in Luke 1:34-35, indicating that the Holy Spirit’s overshadowing of Mary to bring about the conception of Jesus “would also effect the result that he would be called ‘the holy Son of God’” (32).

I sense that Letham himself has undergone (or is undergoing) some rethinking in this regard, and he has been helped by the work of Bruce McCormack (32 n45). McCormack has pointed out “that for Reformed theology the Holy Spirit, not the hypostatic union, preserves the incarnate Christ from the taint of sin,” and Letham notes that he had earlier reported this to be so (n45). Now, however, Letham writes:

But the work of the Holy Spirit and the personalization of the Incarnate One by the eternal Son are not at loggerheads as if they were from disparate sources. The Son and the Spirit act distinctly, yet harmoniously and indivisibly, in all the ways and works of God. Both are involved—with this distinction: the assumed humanity is in personal union not with the Holy Spirit but with the eternal Son (32 n45).

The plot thickened a bit for me when Letham reviewed the contribution of Justinian I. When Letham stated that Chalcedon meant that “the single hypostasis in Christ was the hypostasis of both the divine and human natures” (33), I didn’t blink. As long as I can remember, I have read the Chalcedonian Definition with that meaning in my mind. But I did blink when Letham went on to state, as a consequence of Christ’s humanity having no separate hypostasis of its own, that “Christ unites all mankind—not merely a single human being—to the divinity” (33 [emphasis mine]).

Hmm, I thought, that is not the way I have been thinking about it. As I mentioned above, I have specifically stated that, in fact, this was not so, but that Christ took upon himself a nature like yours and mine, when he became “of one substance with us.” Does the fact that the human nature of Christ was impersoned by the eternal Son of God entail that the Word has united “all mankind” to divinity? I have not thought so, hitherto, but Letham apparently does, and I am now unsettled about it. What does occur to me, however, is that the understanding of the incarnation which Letham puts forward here, would ground quite significantly the more robust affirmation of the universal sufficiency of Christ’s atoning work, which I have recently adopted. In that connection I have begun to speak of a “double intent” in Christ’s atoning work, and I can see that this understanding of the incarnation coheres well with that view of the atonement. This is particular intriguing because, in previously making a case for the single, limited, intent of Christ’s atoning work, I benefited significantly from Letham’s labor in The Work of Christ. I now wait with baited breath to see whether Letham’s own understanding of the atonement has undergone any modification, as a result of this work on union.

In the future, I will be pondering anew my understanding of the incarnation, and particularly of the implications of the union of the Word with human nature for deification, including entailments both for humankind and for the salvation of God’s people. I have a hunch that coming chapters in this book by Letham will further stimulate my thinking in regard to these matters. This is what I enjoy about reading, and about blogging my way slowly through good books.

2.  The universal and particular entailments of Christ’s incarnation

What I have stated already has put this matter on the table, but an aspect of the issue came to focus for me especially when Letham spoke of Christ’s assumption of humanity in terms of both his headship of the church and mediatorship of creation (39). It looks as though this doctrine warrants our speaking of the incarnate Word as having two relationships to Adam, universal (mediator of creation) and particular (head of the church). If so, these relationships ground the covenant of creation (“Adamic covenant”) and the new covenant. Once again, I see in this construct a foundation for (or at least a coherence with) the distinction between the universal sufficiency and the particular efficacy of Christ’s atoning work.

This issue arose quite keenly for me as I read Letham’s summary of the chapter on the incarnation, where the universal and the particular are not clearly distinguished. For instance, Letham begins the section with this statement: “Christ has completely identified himself with us. He is one with us. He everlastingly took our nature into personal union. He is at the Father’s right hand in our flesh” (40). All of that is universal, true of all humanity. The “us” in those statements is all human beings. It is this, I suggest, that grounds common (non-saving) grace as a fruit of the atonement. It is because “Christ has united himself to us in the incarnation,” that “we can be united to him by the Holy Spirit” (40), but this does not happen for everyone, and there we see the particular intent of Christ’s atoning work, which is effected through effectual calling by the Spirit. Accordingly, Calvin spoke of the incarnation as “a weak union in the sense that it is not by itself redemptive” (41, citing Institutes 3.1.1). It looks as though there is a broad (weak) and a narrow (strong) union, each of which produces different fruit for the humans involved.

All in all, I think that Letham has given us fine material in these early chapters of the book. I look forward to what follows, and I hope to make progress in resolving some of the questions which I have stated here.


By Terrance Tiessen

I am Professor Emeritus of Systematic Theology and Ethics at Providence Theological Seminary, Canada.

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