Union with Christ: In Scripture, History, and Theology by Robert Letham explores what many have called the central teaching of the Reformed doctrine of salvation. Indeed, one of the purposes of the book is to unravel the many threads that tie union with Christ not only to personal salvation, but also to creation and recreation, the incarnation, and the Church. Union with Christ, then, is a comprehensive perspective on God’s activity toward mankind, especially toward his elect. Union is not so much a locus of theology in itself as it is a way of relating and integrating the various themes of theology.
Because union is the sort of doctrine that is discussed in relation to other doctrines, Letham does not organize the book according to Scripture, history, and theology. Rather, he arranges the book thematically, incorporating the three components into each chapter. The first chapter, “Creation,” establishes the foundational principles for union: Christ as mediator of redemption and man as the image of God. These two truths provide the cosmic or natural foundations for union, which provide a platform for a higher level of union in grace.
The next chapter, “Incarnation,” develops the theme of union by showing that in the person of Christ, God and man are perfectly united. The history of Christology comes to the fore in this chapter, as Letham retells the early Church’s struggle to articulate the Incarnation as the basis of salvation. As a man Christ had to live in perfect conformity to God’s law, die as a propitiation, and conquer death with new life. However, the Incarnation does not, by itself, ensure our salvation. Christ was united to human nature in general, not to the elect. Thus, the third chapter, “Pentecost,” explains how the Holy Spirit unites the elect to Christ so that they, as individuals and as a corporate body, share in him and his benefits.
So far the book follows a redemptive-historical format, explaining the trinitarian and narrative basis for union. The final three chapters explicate in what union with Christ consists, grouping aspects of union into three categories: representation, transformation, and death and resurrection. The chapter on transformation is masterful. It covers issues relating to the ordo salutis (order of salvation), the relationship between the Greek Fathers and Reformed theology, and the bumpy history of Reformed thought on sacramental theology. It concludes with ten theses on union with Christ and transformation. It is worth reading the book simply for this chapter.
On the whole, though, the book is a bit disappointing. Despite its admirable breadth, logical progression of thought, and interdisciplinary awareness, it possesses one fatal flaw: length. The book is simply too short to develop properly the ideas it contains. Letham’s previous book, The Holy Trinity: In Scripture, History, Theology, and Worship, comprises 551 pages. This one is a miniscule 164. Often, a provocative statement is left unsupported or a significant historical figure is given the most cursory treatment. Detailed exegesis is sorely lacking, insufficiently compensated for with abundant parenthetical citations. Almost all the chapters seem more like sketches than finished products.
Also, the book varies in style. At times, it reads in a popular, almost unscholarly, tone. At others, long strings of Latin obscure the text. For example, Letham is relating a comment by Calvin, “Paul testifies that we are of the members and bones of Christ (Paulus nos ex membris et ossibus Christi esse testatur).” More often than not, the Latin takes up space rather than clarifies a point. A few times, I noticed that something was underlined in the Latin, presumably for emphasis, without any correspondingly indicated emphasis in the English translation. Since I read Latin, I found these choices to be mere annoyances, but I suspect non-Latinists will be much more frustrated by this. The Latin should have been either omitted or moved to the footnotes, except in cases of special significance.
Nevertheless, I am glad I read this book, especially for the chapter on transformation. Letham’s overall approach to union with Christ is highly illuminating, and the germs of many worthy thoughts reside here in nuce. Also, the upside to it being a short work is that if you don’t like it, at least you didn’t invest too much time in it.