“Once people stop believing in God, they start believing in anything” is a misquotation often attributed to GK Chesterton. Most books on contemporary credulousness translate “God” into secular, sociological terms – a circumscribed, solid authority to trust in. But Damian Thompson’s analysis of “counterknowledge”, or fakery in science, medicine and history, is the work of a Christian – the editor-in-chief of the Catholic Herald, in fact – and his religious belief makes it both compellingly original, and riddled with conflict.

Thompson starts off by deploring the unregulated freemarket in websites and books that renders all claims to knowledge equally valid. “Free culture knows no bounds,” says Jimmy Wales, the founder of Wikipedia, the online encyclopedia. How marvellous that sounds. In fact, of course, the new technology’s egalitarianism leads to the tyranny of those websites and gurus that are most skilled at proliferation and presentation. Once hierarchies of expertise are levelled, truth is trampled flat. Creation-Wiki, which propagates Genesis-based creationism, is indistinguishable in layout, font sizes, font colours and graphics from Wikipedia.

Thompson adds an extra controversial ingredient to this familiar complaint – his indignation that so many nonMuslim commentators don’t criticise Islamic fundamentalism, and instead concentrate their fire on American Christian fundamentalism. Plenty of criticism is levelled at Kids 4 Truth, the American creationist website, virtually none at the widely read Islamonline.net, which warns Muslim parents to be vigilant against the indoctrination of their children with “the myths of Darwinism”. In 2006, more than 90% in a poll of UK Muslim students in higher education rejected the theory of evolution; but this atavism is treated as unfortunate rather than reprehensible.

In the field of history, argues Thompson, boundaries of what is to count as fact are also “gerrymandered around people’s sensibilities”. The academic publisher, Routledge, has brought out The History of Africa by Molefi K Asante as a basic textbook, although the professor, invoking the “moral blackmail” of slavery and racism, specifically absolves himself and other Africanists from the constraints of “European” conventions such as methodological rigour.

Counterknowledge is intelligent, angry and funny, but is ultimately hoist by its own petard. Thompson states his allegiance to Karl Popper’s falsifiability criterion (only what can in principle be falsified can in principle be true), but never acknowledges any potential clash between his belief in empiricism and his Catholic faith. He glosses over the church’s historic role in crushing scientific experiment and innovation, and as evidence of the church’s new-found scientific credentials, offers up Pope John Paul II’s 1996 description of evolution as “no longer a mere hypothesis”.

If Catholic theologians no longer ponder how the Virgin Mary could have conceived (via the ear, suggested medieval theologians), this is surely because they no longer believe literally in the Virgin Birth, which could be said to mean that they no longer believe in it at all, or at least have pretty much surrendered to empirical science. But Catholicism always has the authority to backtrack, because its authority is that of faith, not reason.

In fact, as Thompson admits, a cardinal closely allied to the present pope, and himself papa-bile, espouses a sophisticated version of creationism, and there is still the hilarious pseudoscience of a putative candidate for sainthood having to perform three “proven” miracles after death. In denouncing the spawning of pseudo-authorities, Thompson serves two masters that are ultimately incompatible – Catholicism and empirical science. Their greatest clashes may be in the past, but they each continue to exact, when push comes to shove, a unique allegiance. And one, surely, is a candidate for counterknowledge.

Counterknowledge: How We Surrendered to Conspiracy Theories, Quack Medicine, Bogus Science and Fake History by Damian Thompson
Atlantic £12.99 pp256

Times Recommends

• Superfreakonomics by Steven D Levitt and Stephen J Dubner
• The Times picks the 50 best paperbacks of 2009
• Vincent van Gogh’s letters show the soul of the artist