In this book, which began as a doctoral dissertation at the University of Aberdeen, Darren Sumner sets out to correct what he perceives to be the inadequacies of classical christology as it developed up to and beyond Chalcedon. These include an emphasis on the Logos asarkos and a tendency to instrumentalise Jesus’ human nature. The former perspective would prohibit theologians from acknowledging that Jesus’ human nature is ‘essential’ to his divine being. The latter would tend towards a kind of Nestorian perspective which would keep Jesus’ human being from being too influential upon his divine being. His claim throughout is that we can learn from Barth's actualistic and historicised christology that one must no longer maintain that the Logos is anything more than a ‘counterfactual’.

In five carefully constructed chapters, Sumner presents his case by exploring what he terms the ‘identity problem’, i.e. the problem of just how to identify Jesus Christ in his true humanity and true divinity without confusing, separating or mixing the two natures or as he prefers, following Barth, the two ‘essences’. In the first chapter he discusses models of the incarnation in connection with divine immutability, impassibility and kenosis. These become the test categories for his conclusions in the final chapter, which then become the lenses through which he demonstrates how he believes that Barth offered his own critical retrieval of the classical christological tradition. In chapters 2, 3 and 4 Sumner offers his take on: (1) Barth's response to the Logos christology in relation to his early and later theology; (2) Barth's positive doctrine of reconciliation which includes his views on election, covenant, time and eternity, the communicatio idiomatum, the extra Calvinisticum and the status duplex; and (3) just how Chalcedonian Barth's early and later christology was.

Readers will learn a great deal about various patristic perspectives on the incarnation and how key figures such as Athanasius, Cyril, John of Damascus, Maximus the Confessor and Thomas Aquinas thought about divine impassibility, immutability, kenosis and the Logos in relation to Christ's human nature. They will also be interested to see that, while Sumner believes there is a ‘relatively high degree of consistency between the Christology of the earlier and later volumes of the Church Dogmatics’ (p. 9), he nonetheless follows a contemporary trend by insisting that the later Barth had no place for the Logos asarkos and consequently, that the later Barth so identified the immanent and economic Trinity that Christ's divine and human natures should be understood to exist in a mutually conditioning relationship (pp. 96, 131, 135, 188). This claim unfortunately leads to a number of seriously problematic statements which jarringly appear at crucial points in the book.

For example, we are told that ‘Barth's actualism requires that there is no sense in which the divine Logos is not Jesus Christ, the God-human’ (p. 10). Hence, the Son ‘has, in a sense, always been human’ (p. 210). Could this mean that the eternal Son or Word never existed without his humanity? And if that is true, is Sumner arguing that Jesus’ divinity is in some sense constituted by his humanity? Sumner claims that history does not constitute ‘the person of the Son’ because in free election ‘God determines the Son to be the incarnate one in eternity (Logos incarnandus)’ (p. 10). But then we are told the following: ‘That in Himself God may exist otherwise is rendered a deeply relativized counterfactual – true, insofar as it speaks to the divine possibility, but not as it refers to God as God has determined Himself to actually exist’ (p. 10). Later we are also told that ‘Because God has determined Himself for creatures, for incarnation and redemption, this event is constitutive of the Son's identity’ (p. 204). This series of confusing assertions leads to the theme of the book: ‘in the incarnation of the Son the triune God has freely made humanity itself to be essential to the divine life’ (p. 10). Is this really Barth's theology? To answer that question let us consider just three key intertwined issues: (1) how Sumner understands Barth's view of primary and secondary objectivity; (2) why Barth unequivocally and consistently rejected any notion of mutual conditioning between divine and human being and action; and (3) Barth's understanding of the relation between the immanent and economic Trinity.

Sumner contends that primary and secondary objectivity are to be understood in terms of revelation and not ontology since they refer to God's immediate knowledge of himself and the knowledge we have of God, which is mediated (p. 126). Hence, it would be wrong to assume that Barth would use those categories to speak of the distinction between the immanent and economic Trinity. Since, for Barth, ‘being and act are equally basic and interdependent concepts, we may say that – by virtue of God's freedom – the divine disclosure of Himself that takes place in the incarnation determines the sort of God He is in eternity’ (p. 127). Here is the first major problem: on the one hand Sumner claims that history does not constitute the divine being of the Son; yet on the other hand, he asserts exactly that. How can this happen? It happens, I suggest, because he does not distinguish between God's being and act within the immanent Trinity and in the economy, which led him to conclude that God's disclosure of himself in the incarnation ‘determines the sort of God He is in eternity’. He then insists that primary and secondary objectivity cannot refer to the immanent and economic Trinity, respectively, because the distinction does not refer to ‘how God is but how God is known’ (p. 127). Hence, ‘God's primary objectivity is simply God's self-knowledge, not His inner life’ (p. 127). Nothing, however, could be further from the truth. A cursory reading of CD II/1 indicates that Barth very clearly refers these categories to the divine being and not just to how we know the divine being: ‘In His triune life as such, objectivity, and with it knowledge, is divine reality before creaturely objectivity and knowledge exist. We call this the primary objectivity of God’ (CD II/1, p. 16). These statements, of course, pose a major problem for Sumner's basic thesis, since if God's objectivity is reality before creaturely knowledge and reality exist, then one could never say that humanity is ‘essential’ to God or that their relationship is a mutually conditioned one. This is not an isolated issue in this book. It reappears with some frequency.

Sumner believes that while Barth may have opposed any mutually conditioning idea of divine and human being earlier in the Church Dogmatics, Barth explicitly maintains that the two natures in Christ are in fact mutually determined in CD IV/2. But even as he explains this by saying that the relation of the two natures is an irreversible relation, Sumner is forced to conclude that for Barth in CD IV/2 ‘Christ's divinity is therefore not conditioned by his humanity, strictly speaking’ (p. 188). Why then does Sumner embrace this idea throughout the book? I suggest that it is because he has in fact accepted the proposition that, when Barth made Jesus Christ the subject of election, he no longer wished to advance any notion of a Logos asarkos or a being of the Son hidden in the bosom of the Father (in primary objectivity). Hence, Sumner claims that Barth historicises the Son's eternal being; consequently, ‘The Logos asarkos is eternally the Logos incarnandus’ and ‘Jesus Christ, the God-human – may be confessed as eternally preexistent. Indeed, Barth came to believe that only Jesus – and not an abstract Logos – may be confessed as the eternal Son and Word of God’ (p. 203). In arguing that, for Barth, ‘God the Son has His eternal being in the determination for incarnation, for revelation and reconciliation’ (p. 203), Sumner leaves his readers with the question of whether or not God really could have been God without us. The answer of this book is a clear ‘No’. Barth's answer was a clear ‘Yes’ because God's determination to be God for us was the beginning of his ways and works ad extra and not an eternal election which constituted his eternal triune being. It was a decision for his relations with us and not a determination to become the eternal God he always was and is as Father, Son and Holy Spirit.

There is much to ponder in this book. It offers a lively and thought-provoking analysis of just how far theologians can go in recognising and explaining the identity of Jesus Christ. This is a book which is very much worth reading just because it is so provocatively written. No one will come away from this book without having to rethink christology once more. And we are all indebted to Darren Sumner for challenging us to do just this.