Paul Vallely: God knows why Dawkins won't show

Our leading atheists prefer abuse to argument when faced with a tough-talking Christian opponent

There will be an empty chair in the Sheldonian Theatre in Oxford on Tuesday, unless Richard Dawkins turns up to occupy it. The high priest of atheism has been invited there to debate with America's leading Christian apologist, the analytic philosopher and theologian William Lane Craig. But the evolutionary biologist has declined the invitation. In response, the promoters of the event have placed adverts on the city's coaches which sarcastically echo those splashed on London buses a couple of years back announcing: "There is probably no God. Now stop worrying and enjoy your life." The new version says: "There is probably no Dawkins. Now stop worrying and enjoy Oct 25th at the Sheldonian Theatre."

The erstwhile Professor for Public Understanding of Science was stung into a response, in a newspaper article. Craig, he said, was a "deplorable apologist for genocide" with whom he would not share a platform. The genocide in question is that of the Canaanites in the Old Testament Book of Deuteronomy, which you might have expected our top atheist to point out is of dubious historical accuracy. But then any stick will do to beat a dogma.

In any case, there is another side to the story. William Lane Craig is a formidable debater. He has done battle with celebrity academic atheists including Lawrence Krauss, Lewis Wolpert, Peter Atkins, and Sam Harris. Not long after his exchange with the philosopher Anthony Flew, perhaps the leading atheist thinker of the late 20th century, Flew converted, if not to Christianity, to deism. Harris described Craig as "the one Christian apologist who has put the fear of God into many of my fellow atheists".

Christopher Hitchens said: "I can tell you that my brothers and sisters in the unbelieving community take him very seriously. He's thought of as a very tough guy: very rigorous, very scholarly, very formidable." After a debate in which the two locked horns, one US atheist website pronounced: "Craig was flawless and unstoppable. Hitchens was rambling and incoherent, with the occasional rhetorical jab. Frankly, Craig spanked Hitchens like a foolish child."

William Lane Craig is the Professor of Philosophy at Talbot School of Theology in California. He is a conservative evangelical, but he is smart, with a doctorate in philosophy from Birmingham and one in theology from Munich. He has developed such a reputation that when he began a 10-day speaking tour of Britain on Monday he drew an audience of 1,700 at the cavernous Central Hall in Westminster.

The titles of his UK lectures give a clue to his breadth: "Does God Exist?", "Can We be Good without God?", "The Origins of the Universe – Has Stephen Hawking Eliminated God?", "The Historicity of Jesus's Resurrection". He is unafraid to range across ontological theology and moral philosophy and talks with ease about new developments in cosmology, mathematics and physics. He has a ready command of easy analogy and can be funny. He is a million miles away from the evangelical rhetoric that amuses and bemuses our secularist and modernist establishment. Proof, he says, is not about scientific or mathematical certainty; it is about a cogent and logical argument which is more plausible than what opponents argue.

This is not the style of the Dawkinsites' preferred adversaries. Their debating techniques tend to be catalogues of religion's historical atrocities, coupled with psychological sideswipes about the Tooth Fairy and Father Christmas. Dawkins in the past has been notable for seeking out extreme oddball fundamentalists. He and his followers routinely erect a straw man – defining religion in ways unrecognisable to many mainstream believers – and then knock their caricature to the ground. But Craig is an opponent of a different calibre who focuses ruthlessly on failures of internal logic in his rivals' arguments.

What is striking to the outsider is the ad hominem abuse that has been hurled his way. Dawkins has blogged of his "almost visceral loathing" of Craig's "odiously unctuous, smug and self-satisfied tone of voice". Craig, he says, is a "deeply unimpressive... ponderous buffoon" who uses "chopped logic" for "bamboozling his faith-head audience". On Dawkins's website his supporters have called Craig a "debased freak" and "snakeoil salesman".

When A C Grayling was invited to debate Craig's assertion that, without religion, there are no objective moral values, only social conventions, he scornfully replied: "I would be happy to debate him on the question of the existence of fairies and water-nymphs." So much for the assertion by the British Humanist Association, of which Grayling is a luminary, that one of its core values is "engaging in debate rationally, intelligently and with attention to evidence".

So who's afraid of William Lane Craig? Not everyone. The philosopher Stephen Law, from Heythrop College, gave Craig a good run for his money on Monday by turning many of Craig's arguments inside out and postulating the idea that God does exist but is evil, not good.

Back in the United States, Craig was effectively countered by the cognitive biologist and philosopher of science Daniel Dennett, who was brought to a halt by Craig's relentless syllogisms, reductiones ad absurdum and piling up of complex technical detail. After taking a breath, Dennett replied: "Professor Craig, brilliantly and with a wonderful enthusiasm, takes our everyday intuitions – our gut feelings about what's plausible, what's counter-intuitive, what couldn't possibly be true – and cantilevers them out into territory where they've never been tested. In cosmology, whatever the truth is, it's going to be jaw-droppingly implausible and counter-intuitive in one way or another. Perhaps we are alone in the universe... or perhaps that's not true. Both alternatives are mind-boggling. So you can't use mind-bogglingness as your litmus test."

There is something else. Craig represents a high modernist Christian rationalism which takes no account of the insights of postmodernism. He appears, one philosopher friend said to me recently, never to have really heard Alasdair MacIntyre's questions: "Whose justice? Which rationality?" The hard questions are not all neatly sewn up by logic. Real life is more complex than Craig makes out. And faith is not taught, so much as caught from those few individuals of shining goodness most of us encounter on a few rare occasions.

For all that, Craig is – as the website puts it – the Jedi Master of religious debate. Which is why Dawkins's fellow Oxford atheist, the philosophy lecturer Dr Daniel Came, wrote to Dawkins to say: "The absence of a debate with the foremost apologist for Christian theism is a glaring omission on your CV and is, of course, apt to be interpreted as cowardice on your part." A newspaper article setting out what he would have said if he had deigned to turn up, safe from any response from his opponent, really will not suffice. Margaret Thatcher had a plainer word for it. Frit.