You might be forgiven for expecting a 1,000-page book to be a little self-indulgent. Not this one. The prose is taut and tart, sometimes to the point of breathlessness; and it is an astonishing feat of compression. After all, this book aspires to be a global, comprehensive account of perhaps the most diverse, long-lived, pervasive and powerful movement in human history.
That diversity is the book's most important theme. Although all the usual suspects are here, from Constantine I to John Wesley to John Paul II, MacCulloch has little patience with Eurocentric (or Latin-centric) visions of Christian history. The Eastern Orthodox churches are fully covered; so too (and this is a particular preoccupation) are the bodies cast out by the deeper schism of the 5th century - the Monophysite ("Miaphysite") churches of Armenia, Egypt and Ethiopia, and the Nestorian ("Dyophysite") churches whose scattered presence once reached deep into China.
The great future of non-Latin Christianity has largely faded, but MacCulloch reminds us of its lost power and promise, as well as other teasing, forgotten religious possibilities, such as the failed scheme for joint Anglo-Moroccan colonies in North America. He positively celebrates the riot of religious pluralism in the modern world, and is inclusive of squabbling Christian offspring such as Quakerism, Unitarianism, Mormonism and even atheism ("the ultimate form of Protestant dissent").
And a family is what Christianity is: tied together by history, descent and relationship, not by shared beliefs, hence the three millennia of MacCulloch's subtitle. Christian culture is the child of a mixed marriage between Greek and Jewish culture, and he begins with that vital prehistory. The family historian's advantage, of course, is the ability to spot recurrent patterns in the genes. Music is a particular theme here, whose beat has so often quickened the blood of Christians and whose wordlessness can take over when the intellect is overwhelmed or repulsed.
There is always violence, too, the product of diversity and passion: citing the story of Cain and Abel, MacCulloch notes that the Bible's first act of worship is immediately followed by its first murder. And there are wonderful parallels and synchronicities, too (for example, the similarity of The Book of Mormon to The Lord of the Rings).
But if this is not a family united by its beliefs, it is supremely a family in which belief matters. MacCulloch will not let his readers get away without engaging seriously with theology and recognising that it is serious. The three-way schism of the 5th century, for example, was over the nature, or natures, of Jesus Christ as both God and human. It is hard for modern imaginations to credit that rival theories about this could matter so much, but as we follow the stories it becomes clear that those different theories produced radically different ways of seeing the world. It also becomes clear that all of us in the Latin West are heirs to that struggle, whether we like it or not. Likewise, MacCulloch argues that one of the oddities of modern Christianity (of all kinds) is its this-worldliness and indifference to doctrinal abstraction.
And so, despite all the globalisation and context, one giant still dominates the book. We meet Augustine of Hippo only on page 301, but thereafter he is inescapable: his insights and extraordinary reading of the Bible continue to tower over Latin Christianity to the present. Most of the key convulsions of the Western Church begin with someone rereading or rediscovering Augustine.
Inevitably, in common with Augustine's massive works, this will be a book for dipping into as much as for full immersion. Tasters will miss the bigger picture, but there is plenty for them. MacCulloch writes with great moral seriousness, but also with a waspish wit (Ivan the Terrible's fear for his own soul was "intense and justified") and a sense of mischief that he occasionally lets off the leash (as in his argument that early Christians probably smelled worse than most Romans).
Beneath these vignettes is a grander story of repeated rise, fall and rise again - a cycle that, as his subtitle indicates, he expects to continue. The decline into doubt and pluralism in the post-medieval West is explained with particular power and traced ultimately to the brutal expulsion of Spain's Jews in 1492 (an event that becomes, with bitter irony, the foundation of later Western liberties). Christianity's rise is a deeper mystery. Eurocentric histories have sometimes dismissed it as a fluke, the product of one Roman emperor's idiosyncratic conversion. MacCulloch explodes that by showing how often Constantine's story has been paralleled elsewhere, from Syrian kings beyond Rome's frontiers before Constantine's time, through Ethelbert of Kent to (he wonders?) modern China. What is it that made, and makes, the Christian Gospel so astonishingly appealing? Perhaps history cannot tell us.
A History of Christianity: The First Three Thousand Years
By Diarmaid MacCulloch. Allen Lane, 1,184pp, £35.00. ISBN 9780713998696. Published 24 September 2009