In this short but densely-written book, DeJonge sets about analysing Bonhoeffer's theology of revelation, chiefly as a response to Barth, and with particular reference to Act and being, Bonhoeffer's 1930 Habilitationsschrif. The book is offered as a clarification of much Bonhoeffer scholarship which focuses on the later, post-academic and more popular writings of Bonhoeffer. The main emphasis is on Bonhoeffer's ‘Person’ theology (p. 16) which moves away from the dialectical theology of the early Barth towards a more hermeneutic theology of the presence of the person of Christ. The advantage of Bonhoeffer's method is that the polarities between history and eternity which are so obvious in dialectical theology can to some degree be overcome. After a very detailed reading of Act and being in the context of its theological background in Heidegger and Kant, DeJonge moves into a discussion of Barth's ‘act’ theology. What is clearly brought out is the importance of the confessional dimension of these two giants of twentieth-century theological thought. Barth is read as a Reformed theologian against Bonhoeffer's Lutheranism. What distinguishes Bonhoeffer from Barth is his emphasis that God is not simply a transcendent subject (who ‘spoke’ in Jesus Christ) but a person who is as he is in Jesus Christ and as he exists in the Church (p. 78). Consequently, Bonhoeffer argues that ‘theology should express its humility not through a dialectical thought-form but through its proximity to the present person of Jesus Christ’ (p. 81). Where Barth sees ‘act and being together in the inner-Trinitarian subjective life of God’, Bonhoeffer sees ‘act and being together in the historical person of Jesus Christ’ (p. 114). DeJonge carefully contrasts Bonhoeffer's understanding of Luther with that of his teacher, Karl Holl, as well as with the interpretations of Charles Marsh and Christine Tietz. All this leads DeJonge into a re-evaluation of Christian ethics where theology can be fully orientated to both God and the world. Concrete ethics derives from the person of Christ and the reality of the reconciliation of God and the world in Christ: this means that the divisions between the world and God (the ‘split-thinking’ of dialectical theology) are overcome without being confused (as in liberal theology). In dialectical theology ‘ethics looks to alternate moments in heaven and earth’, whereas Bonhoeffer ‘maintains a unit of God and world in revelation, in the person of Jesus Christ’ (p. 142). This understanding leads Bonhoeffer into the later stage of his career, where he would brook ‘no abstract distinction between the concerns of the Christian and the concerns of the world’ (p. 146). Overall, DeJonge's impressive survey succeeds in showing how Bonhoeffer's theology of discipleship – and ultimately of martyrdom – was rooted in an understanding of the person of Jesus Christ that he developed early in his career.