In keeping with the format of a Cambridge History, this volume deploys an impressive number of academic A-listers, assembled to produce an authoritative treatment. Its chronological scope takes in the period from the end of the Roman empire to the Gregorian reform and the First Crusade, opening with an introduction by Peter Brown giving an overview of the Christian world c. 600, and closing with John van Engen doing the same for c. 1100. The essays, on the whole, show a greater tendency to spill into the period before 600 (particularly in the first chapter, by Philip Rousseau, nicely presenting the late Roman background) than into that after 1100, and in fact sometimes stop just shy of this end point: chapters on the Muslim world end in 1050 to avoid the First Crusade, and the Gregorian reform is left teetering on the edge, discussed in some chapters but excluded from others, or more often only alluded to in conclusion. The book thus essentially considers the period after the end of the patristic era and before the growth of papal monarchy. The biggest risk was always going to be overlap with chapters of the first three volumes of the New Cambridge Medieval History. This is avoided by adopting a different principle of organisation, broadly thematic rather than narrative, with most chapters taking in a very wide geographical and chronological range.

The volume reflects recent historiographical concerns in its emphasis on Christianities in the plural (the ‘formative creativities at work regionally’, as van Engen puts it, p. 629). Interest in plurality leads to a degree of re-balancing in favour of marginal regions. This is above all the case in the chapters contained in the first two parts. Part i (‘Foundations: people, places, and traditions’) is intended to give an introductory tour of Christianity in its various regional forms around the Mediterranean and beyond. Narrative introductions to the Byzantine empire and the Eastern Churches are given in the chapters by Louth and Dorfmann-Lazarev. By contrast, there is much less basic narrative for western European Christian heartlands, knowledge of which seems to be taken rather more for granted. The chapters dedicated to western regions deal mostly with frontiers (as with Charles-Edwards on Ireland, or Shepard's very good chapter on the Slavs). Even Lesley Abrams's chapter on ‘Germanic Christianities’ deals mainly with regions or peoples fairly new to Christianity and, following the implications of the title's adjective (with the use of which the author herself seems at times slightly uncomfortable), concentrates on clashes and accommodations between Christian and non-Christian traditions. Part i and part ii (‘Christianity in confrontation’) thus have much in common: frontiers and cultural clashes are emphasised in both, resulting in occasional overlap (Dorfmann-Lazarev and Griffith, Abrams and Wood). Both show a clear desire not to follow a narrow approach privileging usual suspects such as England, Italy or the Carolingian territories: there is thus rather more here about Poland than about the Carolingian empire, or about Ireland than England. This is in some ways welcome, as it eschews the unbalance characteristic of traditional narratives, though it may also constitute a slight hindrance in using this book as a teaching tool.

Part ii deals with encounters between Christianity and other religions, and between Eastern and Western Christians. Christians and Jews are treated by Bat-Sheva Albert; Christian-Muslim frontiers from Asia Minor to Spain by Hugh Kennedy; Christians under Muslim rule by Sidney Griffith. Kolbaba's chapter on ‘Latin and Greek Christians’ offers a clear outline of relations between Constantinople, Rome and Aachen, and the section ends with an excellent contribution by Ian Wood on missionary activity in northern Europe.

From part iii onwards, these geographically specific introductory chapters make way for essays treating large themes (such as law, asceticism, property, penance) across the whole chronological and geographical spectrum: this is bold, broad-brush, comparative stuff, in fact often done very successfully. Contributors were clearly asked to stretch, and mostly rose to the challenge. Despite this effort to achieve a wide range, it is notable that western Christian heartlands, and Carolingian Francia in particular, here come very much back into their own, and marginal areas feature rather less. These later sections are also, in general, lighter on politics and links with secular authority. This is true even of part iii (‘Christianity in the social and political order’), which contains some very good chapters on Christian institutions: Noble contributes a handy account of church structures and hierarchies; Helvétius and Kaplan a very good chapter on asceticism; Janet Nelson a much-needed and thought-provoking reappraisal of canon law before the Gregorian reform; Rosemary Morris a learned and wide-ranging study of the ‘problems of property’ and of providing for the needs of religious communities East and West. This is followed by two chapters more closely focused on the later end of the period and ecclesiastical reform: Julia Barrow on ‘Ideas and applications of reform’, questioning the aptness of the word for the medieval period, and Dominique Iogna-Prat on ‘Churches in the landscape’, discussing the increasing importance of church buildings as a focus for both worship and settlement in the West, in connection with the new emphasis on the celebration of the eucharist and the formation of the parish.

Part iv (‘Christianity as lived experience’) considers Christianity's impact on the lives of believers. Paxton's chapter, entitled ‘Birth and death’, traces a ‘medieval economy of salvation’ through rites of baptism (also treating childhood and oblation, though not education or catechism), confession, burial and commemoration. Rob Meens further explores means of clearing the divine balance-sheet with a chapter on penance. Peregrine Horden's interesting and informative chapter on ‘Sickness and healing’ brings out the porous distinctions between religious, medical and magical forms of assistance, followed by Lynda Coon's study of clerical and monastic constructions of ‘Gender and the body’. Arnold Angenendt on ‘Sacrifice, gifts, and prayers in Latin Christianity’ focuses on the liturgy of the mass and the various gifts offered in return by the laity. The section ends with Eric Palazzo on ‘Performing the liturgy’, insisting on the need to move beyond the texts traditionally privileged by scholars in this field in order to embrace the ‘multidimensional’ character of the liturgy, and offering a quick tour of some of its physical aspects (textual traditions taking something of a back seat in this presentation): spatial arrangements; various liturgical objects associated with particular clerical positions, including illuminated books; sounds, lights and smells.

Lastly, part v (‘Christianity: book and ideas’) explores intellectual developments. Alain Boureau's chapter is the most theologically-oriented in this collection, charting ‘Visions of God’ from the Christological controversies of the beginning of the period through the filioque debate, iconoclasm, adoptionism and arguments over the eucharist, to the birth of dialectic theology. E. Ann Matter's chapter on ‘Orthodoxy and deviance’ inevitably covers some of the same ground (in somewhat more accessible form), but also includes Godescalc and his predestinarian heresy, Paulicians, Bogomils and the very beginnings of ‘popular’ heresy. Guy Lobrichon on ‘Making sense of the Bible’ explores tensions in styles of exegesis. This is followed by a thorough and instructive chapter by Brubaker and Cunningham on the Byzantine book; a parallel chapter for the West would have been welcome. The rest of this section then moves on to less obviously rarefied social spheres, with strong contributions by Julia Smith (on saints and the launching and re-launching of their cults) and Jane Baun (on ‘Last Things’ and ideas of the next life).

Its thematic structure means that this is not the sort of book to which one would turn as a factual reference work, in order to gain an idea of the evolution of Christianity in, say, Visigothic Spain or the Frankish kingdoms, or to read about the existence or otherwise of an Ottonian Reichskirchensystem: by and large, the discussion is somewhat detached from kingdoms or other secular structures. At its best, this chronological and geographical breadth can turn chapters into something rather more interesting and original than other introductions available elsewhere, allowing authors to make genuinely wide-ranging connections and comparisons; these same features, on the other hand, can also make some of the less densely-written pieces seem slightly superficial. All this makes this volume a less straightforward teaching tool than the New Cambridge Medieval History, but also makes it a less predictable and more stimulating object than most compendia of this kind.