This book is about ecclesiology, about the kind of critical theological reflection that is centered upon the nature and function of the Christian church. The book is rather more about ecclesiology than it is an exercise in the discipline, since much of the time it will be concerned with methodological issues. The aim is not, or not primarily at least, to make a set of ecclesiological proposals. Rather, it is to clear a space within the discipline of theology for some new and more challenging forms of ecclesiology.

However, as Karl Barth never ceased to remind us, theological method should be determined as much as possible by its subject matter if the latter is not to become irremediably distorted. Beliefs about the nature and function of the church on the one hand, and the question of how we should go about doing ecclesiology on the other, bear upon one another so as to determine the kinds of things we can and cannot say about the church. Thus any argument for a methodological proposal about ecclesiology will necessarily involve making some constructive proposals as to what sort of thing the church is and what sorts of things it can and should do. So, too, here. The point is that what I say about the church will be said primarily in order to make a case for how to do ecclesiology, rather than for its own sake. Some things that would be treated within a comprehensive theology of the church, such as the church's ministerial structures, its forms of worship and its relation to Israel, will not be considered.