The Eternal Son

The Eternal Son, Robert Letham, foreword by Ian Hamilton. P & R Publishing (ISBN: 9781629958637) 2025.

Summary: A Christology focused on Christ’s Person, his eternal sonship, and Incarnation, as clarified in councils and more recently.

Robert Letham has written extensively on the Godhead, beginning with a work on the Trinity. This work is the second of a projected three-volume series on the persons of the Godhead, the first being The Holy Spirit. Having in another work addressed the work of Christ, Letham focuses here on the Person of Christ. However, the final chapter, “For Us and our Salvation” does address aspects of Christ’s work.

Letham begins with three chapters which frame out what Christians have historically affirmed concerning the person of the Son. Firstly, he addresses the “Son in the Divine Trinity.” He summarizes developments between the New Testament and Constantinople, in 381. Discussing the Nicene-Constantinople Creed, he focuses on God’s indivisibility, three persons who are one substance, yet distinct persons. He focuses on the divine order, and the idea of the eternal generation of the Son, that from eternity without beginning, the Son is the Son of the Father. Secondly, in the following chapter, “Before The Beginning” he goes more deeply into the Son’s eternal relations with the Father. Then thirdly, in “The Word Became Flesh,” Letham discusses the biblical evidence of the Incarnation.

Chapters 4 through 8 address the controversies that arose related to the person of Christ and the conciliar decisions, post-Constantinople. One of the things that stands out in the controversies with Apollinaris and Nestorius and in the lead up to Council of Chalcedon is the singular influence of Cyril of Alexandria. Cyril defends the eternal nature of the Son, his taking on of human nature in full union, such that all his actions are of one person in two natures. One of the most interesting ideas was that the assumption of a human nature was not problematic for the Son through whom humans were created in the imago dei.

However, Chalcedon did not resolve all problems and led to new ones. Letham discusses the shortcomings of Chalcedon and the continuing challenge of Nestorians and the rise of Monophysites. Also, challenges arose around the two natures of the Incarnate Son willing and acting as one. Letham walks us through Monoenergism and Monothelitism, including a recent revival of the latter. Finally, he summarizes the consolidation of the church’s thought on Christology in both East and West. To do so, he focuses on two key figures, John of Damascus and Thomas Aquinas.

Chapters 9 and 10 then focus on the Reformation and the Post-Enlightenment. The discussion of Luther and Calvin both emphasized their contributions and how at times they could wander from Chalcedonian orthodoxy. The Post-Enlightenment discussion focuses on kenotic theories–what did it mean that Christ “emptied” himself? Letham also discusses theories of peccability. That is, was it possible for Christ, having a human nature, to sin. Letham argues that Christ’s nature was neither a fallen nature or a nature like Adam’s before the fall. “Rather, he lived in a state of humiliation, sinless and righteous but with a nature bearing the consequences of the fall in its mortality, its vulnerability, and its suffering–but not fallen.”

Finally, after his concluding chapter on Christ’s work, he includes two appendices. One has to do with recent thinkers who have resurrected the idea of the adoption of Jesus as Son, particularly as the basis for our on adoption. The second, promoted by David Moffitt, proposes that Christ’s atoning work was not on the cross but when he presented himself as a blood sacrifice in heaven. Letham refutes both ideas.

I found Letham generally clear in his explanations and discussion of different controversies and councils (he also includes a glossary to help us keep our terms straight). In particular, Letham is good at explaining what is at stake with various proposals, and what stands to be lost. He also offers a good summary, as a Reformed writer, of Reformation developments, probably worth a book in itself. Most of all, I feel Letham writes doxologically. He speaks in his introduction of the hope that we might “Behold, the Lamb!” And I found myself often stopping to do just that.

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Disclosure of Material Connection: I received a complimentary copy of this book from the publisher for review.