With this witty and polemical book, Terry Eagleton finally fulfils the promise of his early years as a left-wing Catholic. Here at last is his defence of Christianity as a radical movement comparable to, and compatible with, Marxism. It is prompted by his sense of outrage at the arrogant pronouncements on religion made by those self-appointed guardians of rationality, Richard Dawkins and Christopher Hitchens, whose names he satirically conflates into one entity, "Ditchkins".
Ditchkins believes that religion is infantile, superstitious nonsense that deserves no respect because it provides a false explanation of the world. In doing so, Ditchkins declares himself to be nothing more than a throwback to the 19th-century school of liberal rationalism and, beyond that, the Enlightenment.
He still has not woken up to the fact that scripture is not the same sort of thing as a scientific treatise. Thus, Ditchkins - here, specifically, Hitchens - claims that "thanks to the telescope and the microscope, (religion) no longer offers an explanation of anything important".
This is risible enough as it stands, but Eagleton was never one to resist a humorous analogy: "Christianity was never meant to be an explanation of anything in the first place. It is rather like saying that thanks to the electric toaster we can forget about Chekhov."
So much for the "reason" in the book's title. What about the faith? The very conviction that reason offers all the answers is itself a matter of belief, persuasion ... and faith. For we are dealing with a language that is "performative rather than propositional", and that goes for liberal rationalists in their colleges as much as for devout believers in their churches.
While religious piety can escalate into fanaticism, so too can the secular fetish of pure reason. Here theology has a distinct advantage: reason, for St Thomas Aquinas, is inseparable from ethical commitment, from communal responsibility, from fellow-feeling - in short, from "love".
And so we come, in a roundabout way, to the third term in the book's title: revolution. What Eagleton's reading of the Gospels tells him is that we should not be anticipating the Messianic kingdom (Jesus himself refused to play the expected role of Messiah), any more than the forcible and final establishment of a classless society. Rather, we should be following Jesus' example in identifying with the poor and the persecuted, trying to ensure that there is no more exploitation, hunger, war or torture.
Eschewing violence himself, Eagleton cannot avoid addressing the atrocities carried out in the name of Islam. What he concludes is this: "The solution to religious terror is secular justice." Here he might seem to hover around a contradiction, since he could be read as giving succour to those who say that the Enlightenment would be acceptable if only it had worked. In this connection, he is not apologetic enough for my liking about Karl Marx himself, who notoriously praised capitalism for its rapid process of industrialisation because it fitted into his own progressive scheme.
That said, it is reassuring to see Eagleton conclude his book with a brief defence of the "tragic humanism" that he sees as the necessary alternative to the absurdly confident "liberal humanism" of Ditchkins.
Moreover, as someone who agrees with Michel Serres that what we need is an ecologically informed "religion of the world", I am particularly pleased to see Eagleton express more than once his concern about the damage that humanity is doing to nature in the name of progress.
Perhaps in his next book, we may see him espouse a politics that is as much green as red, and a theology based not only on Aquinas but also on St Francis of Assisi and Hildegard of Bingen.
Reason, Faith, and Revolution: Reflections on the God Debate
By Terry Eagleton. Yale University Press, 192pp, £18.99. ISBN 9780300151794. Published 28 April 2009