Although John Howard Yoder died in 1997, Theology of Mission is the latest of at least a dozen books published posthumously in his name. Its contents come from a course Yoder taught between 1964 and 1983 at Associated Mennonite Biblical Seminaries, transcribed and edited by Gayle Gerber Koontz and Andy Alexis-Baker, based on tape recordings and lecture notes. The result is a book which is immediately essential for interpreting Yoder's thought and a contribution in its own right to the now ascendant field of missiology.

Yoder frames the book with a set of questions at the intersection of theology, mission and church (p. 36), which, understood as practical undertakings, he uses as critical interlocutors in order to discover the difference that ‘theologizing in the context of mission’ makes (p. 44). The crucial difference, in Yoder's view, is ecclesiological. As he writes in chapter 7, the book's fulcrum: ‘Different understandings of the nature of the church illuminate and shape mission questions and issues’ (p. 145). Yoder casts his vision (pp. 149–54, 175–81) of the believers’ church in contra-distinction to the Christendom model, focusing on such issues as baptism, discipleship, organisation and war. Underwriting and governing these is the bedrock difference concerning ‘the relationship of church and world’, since for the free church tradition ‘making a clear distinction between them is the presupposition of mission’ (p. 159).

Here is Yoder's normative stance, at once ecclesiological and missiological (which for him are two sides of the same coin); it animates everything constructive and critical he says in the rest of the work. Yoder is convinced that the free church perspective has the power to shed new light on old problems and contemporary challenges, and sets about showing how by bringing this fully ramified outlook to bear on numerous traditional missiological topics.

The book follows a loose three-part progression. Chapters 1–6 treat texts and themes from the Bible (and, in one chapter, from systematic theology) concerning mission, focusing especially on Paul's letters and Acts. Chapters 8–18 address ecclesiological issues such as the church's missionary nature, its call to be responsible, its locality, its ministry and so on. Finally, chapters 19–23 consist of what Yoder calls ‘Christian theology of religions’ (p. 338), discussing varieties of universalism, religious pluralism, post-Christian religious traditions and the unique status of Judaism as a ‘non-non-Christian faith’ (pp. 386–98).

The book's origins are not a mystery; it can read like a classroom sequence of topics, because it is. And Yoder's diagrammatic method – question, diversity of views, criticisms, Radical Reformation perspective – is a double-edged sword. On the one hand, it frequently fulfils its aspiration to represent the field fairly and accurately, and to give voice to competing claims. On the other hand, it too often descends to caricature and simplistic generalisation, usually regarding the church after Constantine. The bogeymen of ‘speculative theology’ (p. 398) and Neoplatonism (p. 351) are never far away, while Yoder at one point actually glosses ‘New Testament Christianity’ as ‘believers church Christianity’ without qualification (p. 298).

Theology of Mission is, for all that, an outstanding achievement. Yoder was decades ahead of his time in his sense for the global mission situation and towering in his command of the relevant theological issues. For those convinced that Christendom, for all its virtues and accomplishments, was at root an ecclesiological mistake, Yoder makes clear the alternative implications for the church in its witness among the nations – a witness which, unsurprisingly, makes Jesus of Nazareth its shape, substance and standard. This book should challenge traditional missiologies, forcing them to reckon with the believers church perspective, even as it offers a new and invigorating introduction, for theologians and Yoder scholars alike, to the perils and promise of the missio Dei.