A week or so ago I discussed my new book Darwin's  Angel (a riposte to his God Delusion) on the BBC's Today programme with Professor Richard Dawkins. The exchange lasted barely six minutes, but the debate has continued on a variety of websites (including, hopefully, this one).

My quarrel with Professor Dawkins focuses less on arguments for the existence of God than on the potential social and political consequences of   demonizing religious believers. His argument that Jesus' message to love one's neighbour did not apply to non-Jews is bad enough. But he has also compared all religious believers with disease carriers, and suggested that educating children in the Catholic faith is worse than paedophile abuse.  He claims, moreover, that there is no such thing as "mild" faith, since all faith can turn to extremism.

The historical precedents for comparing groups of religionists with disease carriers are as obvious as they are deplorable. In the 1920s and 1930s the metaphor was used in Germany to suggest that Judaism threatened the healthy body of society. The notion of quarantine and purges soon followed. Professor Dawkins does not subscribe to such solutions for religion, but the influence of his views on less well meaning groups cannot be discounted. Given the negative social and political inferences that can be drawn from depicting religion as a disease, I wanted to ask Professor Dawkins on air whether he thought that religious believers should be excluded from pluralist civil societies.

Dawkins vehemently denied that he had ever written that religion was like a virus: "It is complete nonsense to say that I liken religion to ... I don't know what it was you said, something terrible ... a virus." Then he added: "I have likened it to a virus, but that's a very special point." More on that "special point" in a moment.

On the "worse than" paedophile abuse claim, he also denied that he had  written any such a thing, or that he had ever written that mild faith is equivalent to extremism. "I never said anything remotely like that," he insisted. "What I said is that religious faith, teaching people that faith is a virtue, that believing without evidence is a virtue, is dangerous, because when it gets into the wrong hands it can lead to extremism."

How do these disclaimers on the Today programme stand up to what he has actually written?

Dawkins first suggested that ideas could behave like biological entities in his The Selfish Gene (1976), where he wrote of the transmission of  phenomena  he calls "memes" - cultural habits, ideas, and fashions, which survive and thrive like genes in natural selection.  In time, others, such as the psychologist Nicholas Humphrey and the philosopher Daniel C. Dennett, altered the metaphor for memes from genes to viruses. By the time Dawkins published his collection of essays The Devil's Chaplain in 2003 he too had adopted the viral imagery in his anti-religion rhetoric, and the metaphor would be used again on pages 218-219 of The God Delusion where he describes religion in terms of an "infection" of the brain.

In the chapter titled "The Infected Mind," in The Devil's Chaplain he develops the virus metaphor in detail. He starts by likening the transmission of ideas to computer viruses, but by page 135 the image shifts to that of a biological infection, "a virus, or any sort of parasitic replicator."

On page 136 he refers to human brains and "child brains" in particular as friendly mediums or hosts for certain kinds of cultural viruses, and on the following page he embarks on an extended description of religion as an "epidemic" of replicators, referring specifically at one point to Roman Catholicism.

"We expect that replicators will go around together from brain to brain in mutually compatible gangs. These gangs will come to constitute a package, which may be sufficiently stable to deserve a collective name such as Roman Catholicism or Voodoo. It doesn't too much matter whether we analogize the whole package to a single virus, or each one of the component parts to a single virus."

Dawkins claims that even scientific ideas spread like memes, but scientific ideas, in his view, are beneficial, or at least harmless, whereas religious memes are dangerous.

On the same page he develops an extended medical conceit for religious belief. He speculates, for example, "how a medical textbook might describe the typical symptoms of a sufferer" of a religious inspired "mind virus". On page 138 he talks of religious believers as "faith sufferers",  and as "patients" with "symptoms". And he refers to himself and his associates as "we doctors." By page 141 he expounds the "list of symptoms that someone afflicted with the mental virus of faith, and its accompanying gang of secondary infections, may expect to experience." The "symptoms" include intolerance, violence, and murder, as well as hostility towards "scientific reason which could function rather like a piece of antiviral software."

If this is what he means by employing the viral metaphor only as a "special point," then I am not encouraged to withdraw my accusation that he demonizes and depersonalizes religious believers by comparing their convictions to a cultural virus or disease.  

Next the "paedophile" comparison. On page 356 of The God Delusion he writes that while giving a lecture to an audience in Dublin, the subject of sexual abuse by Catholic priests arose. "I replied that, horrible as sexual abuse no doubt was, the damage was arguably less than the long-term psychological damage inflicted by bringing the child up Catholic in the first place."

But on the programme he said: "I haven't said that it's worse than paedophilia. I said that in one respect labelling children with their parents' religion when they're too young to know what they believe is a form of child abuse." The anodyne gloss by no means coincides with his own self-reported account in his book.  

Finally, the question of mild and extreme faith. "Faith is an evil," he writes on page 347 of The God Delusion, "precisely because it requires justification, and brooks no argument." On the programme he proclaimed, "Of course I am not saying that all religious people are evil, or all religious people are extremists."

And yet, he writes on pages 345-6:

"The take-home message is that we should blame religion itself, not religious extremism – as though there were some kind of terrible perversion of real decent religion... I do everything in my power to warn people against faith itself, not just against so-called 'extremist' faith.  The teachings of moderate religion, though not extremist in themselves, are an open invitation to extremism."

The debate continues. But I am at least comforted by the fact that, when challenged on the programme, Professor Dawkins explicitly recanted, at least in part, some of the views quoted above. The question now is whether he will recognise the far reaching implications of those views and delete the relevant sentences from future editions of his books.   

John Cornwell is Director of the Science and Human Dimension Project at Jesus College, Cambridge. His book, Darwin's Angel: An Angelic Riposte to The God Delusion is published by Profile. The article was published in The Tablet on 21st September. His debate with Richard Dawkins on the Today programme can be heard by clicking here.