Black Mass: Apocalyptic Religion and The Death of Utopia by John Gray is one of those books that has attracted wildly differing reviews.

Much of the book is taken up with detailed accounts of the players and actions in and around the Iraq War, not least Tony Blair - since this disaster exemplifies Gray's thesis, that utopian politics leads to human misery and catastrophe. An anecdote that Gray used in a talk last week adds another dimension. When Karl Rove occupied a few rooms in the White House that had previously been used by Hilary Clinton, from which to run one of his election operations, he had them exorcised by a priest. In other words, even in the most self-confessedly secular state, religion re-emerges in the most unlikely places, and like Freud's repressed desires, often with powerfully disturbing consequences.

Gray also argues that since the Enlightenment and the French Terror, violence has come to be seen as a tool of progress, as opposed to an option of last resort as Just War Theory has it. This was obviously the case in Communist Russian and Moaist China but also obtains in neo-conservative America and Britain. This is a religious belief reinvented since it is based upon apocalyptic myths, in which the last days will witness horrors before the new age is born; violence is a necessary even desirable stage through which to pass. Even atheistic humanism doesn't escape this synthesis of two apparently innate human capacities - religion and violence: its myths of progress - that mistake the accumulation of scientific knowledge for the advancement of humankind - are purged of doubt and so cannot fundamentally doubt themselves.

It is possible to question some of the scholarship Gray relates. For example, he is pretty emphatic that religio-political utopianism is a Christian invention whereas, if I remember my Old Testament lectures correctly, the Apocrypha books of the Bible are Jewish and inspired the BC Maccabean revolt. However, I don't think these details undermine the broad thrust of his argument.

In one of the best aimed jibes in the book, Gray argues that Richard Dawkins, Daniel Dennett et al - the evangelical atheists - are really members of a late Christian sect: only someone from a Protestant culture could believe that people can be changed if only they would change their beliefs about the world. It is the same dynamic as the evangelical who believes that someone becomes a new person if they rationally accept Jesus Christ as their personal Lord and Saviour.

The book is pessimistic in the philosophical sense. Though reading it is invigorating as well as depressing in the way that relentless honesty can be. Gray ends on the need for realism. When I asked him about this, he added that the biggest need for human beings is that of self-knowledge and humility, since the narratives of progress and the like which we tell ourselves, often lead to self-delusion and hubris. I would add that if science has provided us with a tremendous method to gain knowledge of our existence but only in one particular sphere of it, then we also need to recover the ways in which human beings have developed an understanding of the limits of knowledge - the traditions of Socrates, the apophatic theologians and perhaps today psychoanalysis.

In other words, the problem today is not simply that religion has reinvented itself for a secular world, since it always will reinvent itself for new social and cultural conditions. Rather, it is that this particular reinvention has left us mostly or only with 'bad religion' - the religion of hubris.

Which brings us back to the wildly differing reviews Gray has received.

For example, in the Guardian today John Banville calls the book 'brilliant but frightening'. Whereas in the Telegraph today, Kenan Malik calls it corrupting and cynical. In the Independent, Toby Green said it was 'meticulous and persuasive'. Whereas in the Sunday Telegraph last week, Damian Thompson called it 'bollocks'.

Presumably the book provokes such extreme reactions because it either powerfully chimes with or offends against the worldview of the reviewer. Believers in the Enlightenment, in reason and progress, in the transparency of human beings to themselves, in the end of religion will loathe the book - not least because it deconstructs their convictions too. But those who sense that the Enlightenment, reason and progress, psychological self-knowledge and the death of God are not the quick wins for humanity they are cracked up to be, and not even steps on the march towards a better tomorrow, but rather profoundly ambivalent states of affairs, will find Gray articulating their fears for them and unveiling more.