This polemical work claims that Christianity, rather than the barbarian invasions and the breakdown of the Roman Empire in the west, was the main cause of the Dark Ages. Even if the claim is sometimes overstated - as some reviewers acerbically allege - the tale of the defacement and destruction of much of the classical world's art, literature and science by ignorant, fanatical Christians is appalling - the later cultural achievements of Christianity notwithstanding.
It is noteworthy that the ancient philosophers were unimpressed by this new religion, which was, by the way, the imaginative creation of Paul and his followers, rather than of Jesus himself. The philosophers tended to be rational pursuers of truth, who correctly saw that the Christians were irrational pushers of dogma. Thus, the triumph of Christianity in the fourth and fifth centuries was not the unalloyed blessing we were led to believe it was in school divinity classes.
On the whole, I am inclined to agree with Nixey that the pagan world was preferable to the Christian world that superseded it. And I am not swayed by arguments that seem to suggest that, because the pagans sometimes behaved as badly as the Christians, I don't have a convincing case. Perfection is not a sine qua non for superiority. (Likewise, I do not have to construct a "myth of the Andalusian paradise" to maintain that life in Spain was better under the Caliphs than under the Inquisitors.)
Another interesting fact is that the Christian depredations didn't stop with the extirpation of paganism. On several occasions in history - most notably during the periods of Byzantine iconoclasm - Christians turned on their own traditions and systematically destroyed their own artworks. As recently as the 17th century, Christian zealots were bashing the noses off statues in Christian places of worship. As A. L. Rowse says in Reflections on the Puritan Revolution, "It is impossible to do justice to the vast subject of the devastation in [English] parish churches - especially of stained glass, sculpture in wood and stone, monuments and brasses - throughout the length and breadth of the land . . ."
Much as I detest iconoclasm, I would have been prepared to forgive the Christians for what they did in the fourth century if they had, indeed, ushered in "the Kingdom of God" - a society in which an honest attempt was made to live according the principles enunciated in the Sermon on the Mount. Instead, all we got was a continuation of the bloodthirsty power struggles, but in a bleaker, more impoverished world.
* The Darkening Age: The Christian Destruction of the Classical World, by Catherine Nixey