Voltaire wrote that ‘if God did not exist we would have to invent him’. A more modern version might claim, ‘if God did not exist, the publishing industry would have to invent him’ – even if only to argue that he did not exist. Faith endures among the masses but is out of fashion among bien pensants. The biologist Richard Dawkins wrote the bestselling The God Delusion, which is, as its title suggests, scathing about the possibility of a supreme being. In God Is Not Great, the journalist Christopher Hitchens applies his intellectual rigour to dissecting the texts of the major religious faiths, arguing that they have hindered, rather than speeded up, human progress.