Whatever happened to natural law in the Reformed theological tradition? Van Drunen traces the development of the doctrines of ‘natural law’ and the ‘two kingdoms’ (‘spiritual’ and ‘civil’), along with their interconnectivity, that once played a central role in Reformed social thought, and which, he argues, should do so again. The author is uniquely well-equipped for this task, having expertise in theology, law and ethics. After an introductory chapter in which the author establishes the need for the study (‘Natural Law, the Two Kingdoms, and the Untold Story of Reformed Social Thought’), things get quickly underway in Chapter 2 (‘Precursors of the Reformed Tradition’). This considers the antecedents of ‘natural law and the two kingdoms’ in pre-Reformation thought by way of patristic and medieval theology. The usual suspects (Thomas Aquinas, Duns Scotus and William of Ockham) are rounded up for the discussion of ‘natural law’; whilst discussion of the ‘two kingdoms’ incorporates Augustine's ‘two cities’ (of God and Man), the general paradigm represented by the ‘two swords’ doctrine (distinguishing civil and ecclesiastical powers), and William of Ockham's alternative, anti-Papalist, view; before locating Martin Luther in the history of these ideas.

Chapter 3 (‘Reforming Natural Law and the Two Kingdoms: John Calvin and his Contemporaries’) considers how early Reformed theologians took up and applied these ideas, with particular focus on Calvin, noting both his continuity with past traditions, and his departures from them. Chapter 4 moves on to a study of ‘Natural Law in Early Reformed Resistance Theory’. This is presented as a case study in how early Reformed Christianity applied its convictions about natural law to particular social and political situations, with reference to the writings of the ‘Marian exiles’ and the Huguenot refugees. As if the preceding chapters were not challenging enough, in terms of their breadth of material, Chapter 5 faces the considerable task of evaluating the role of ‘natural law and the two kingdoms’ in Reformed doctrine and practice during ‘The Age of Orthodoxy’. The author is necessarily selective here, choosing to focus on representative figures (Johannes Althusius, Samuel Rutherford and Francis Turretin) and documents (The Westminster Confession of Faith and Catechisms). He finds considerable continuity between Reformed orthodoxy and Calvin (as well as other early Reformed theologians) on many points, including belief in the interdependency of ‘natural law’ and the ‘two kingdoms’.

The book turns next, in Chapter 6, to consider how subsequent Reformed thinkers handled this theological inheritance, with reference to theocratic New England (and John Cotton), Revolutionary-era Virginia, and nineteenth-century Presbyterian debates regarding the spirituality of the church. The nineteenth-century brings van Drunen, inevitably, to Abraham Kuyper; in Chapter 7, the author argues that, although Kuyper did not explicitly use the language of ‘natural law’ and the ‘two kingdoms’ to organise his cultural and political thought, his use of categories such as the divine ordinances, and common and special grace resembled these doctrines, in significant ways. As van Drunen sees, Kuyper stands ‘somewhat ambiguously’ (p 278) in the Reformed tradition regarding ‘natural law’ and the ‘two kingdoms’. In that sense, Kuyper represents an ‘ambiguous transition’, according to which later Reformed thinkers sought to resolve ‘the ambiguity in Kuyper's thought in a direction that in fact rejected the Reformed natural law and two kingdoms tradition’ (p 278). A striking example of this rejection, from the twentieth-century, is Karl Barth's criticism of the two doctrines, which is the subject of Chapter 8. In the light of the book's argument thus far, it is apparent that the author sees Barth as representing ‘a rather radical break from the earlier Reformed tradition …’ (p 347).

Chapters 9 and 10 examine aspects of the Kuyperian legacy in the work of Herman Dooyeweerd and North American Neo-Calvinism (Chapter 9) and Cornelius van Til and the Van Tillians (Chapter 10); the former, van Drunen argues, amounts to ‘another version of a break with the earlier Reformed tradition’ (p 347), whilst van Til's theology in relation to ‘natural law’ and the ‘two kingdoms’ is deemed by the author ‘rather ambiguous’ (p 421). The author takes heart, in the concluding chapter, from more recent writers who have questioned Reformed disinterest in these neglected doctrines, and suggests how their recovery could contribute to Christian social engagement. The result is a richly-textured overview which confidently absorbs an impressive sweep of history, combined with carefully-nuanced presentations of complex and controversial theological positions, all without overwhelming the reader. The book is extremely well-organised, with van Drunen's choice of conversation partners clearly illuminating the broader argument. The book's (necessarily) descriptive approach is no mean feat, considering the sheer range of positions adopted by scholars on each figure under discussion, and his navigation of the voluminous primary and secondary literature is masterly: even so, he still finds room for critical analysis. The author hopes, in the near future, to provide ‘a detailed, biblical, theological and ethical defence of the Reformed natural law and two kingdoms doctrines, revised in certain respects and applied to important concrete social issues’ (p 14): this book provides the ideal launch pad. Van Drunen has written the book he always wanted to read; as such, it is transparently a labour of love that could breathe new life into Reformed visions of the church, politics and culture.