This is more or less the talk for my contribution to the Edinburgh Book Festival event this evening, 'The Rise of Atheism'.

Is atheism another fundamentalism? At the very least, I would say there are clear fundamentalist strains within what has been called the new atheism. For example, the word ‘fundamentalism’ comes from a series of pamphlets called The Fundamentals that were published by American evangelicals during the 1910s and insisted on Christians believing certain things like the inerrancy of the Bible. Today some atheists assert fundamentals that they say any rational, enlightened human being should believe ??" such as no supernaturalism, science as the only grounds for knowledge, the indisputable truth of Darwinism and so on. So in that sense they are fundamentalist.

Also, it has often stuck me that anyone critiquing Darwinism these days must first make clear that they do belief in evolution, lest they be mistaken for a secret intelligent designer. And then there is the Richard Dawkins phenomenon. There is certainly something of an American-style revivalism around Dawkins. You can see that if you take a look at his website.

A slightly different problem I have with these atheists is their claim to be the true heirs of the Enlightenment. There was certainly a side of the Enlightenment that was militantly atheistic. For example, in the eighteenth century it was quite fashionable to have pictures of the sun chasing away clouds on the covers of philosophy books. The shining sun was reason; the dispersing clouds superstition.

However, the two greatest minds of the Enlightenment, David Hume and Immanuel Kant saw things rather differently. For Hume, scepticism was the natural position for the Enlightenment thinker ??" scepticism about religion for sure, but scepticism about the fundamentals of science too. And alongside superstition, Hume also objected to what he called enthusiasm, defined as ‘presumption arising from success’. That could apply to triumphalist rationalism and science as much as religion.

Kant found Hume’s scepticism profoundly unsettling. He wanted to put things on a firmer foundation. And he did so, but only by writing Critiques. In these Critiques, the key issue was understanding the limits of human knowledge. When Kant said that Enlightenment was maturity this is what he meant. So we have Enlightenment as scepticism or limit. On both counts, the new atheists seem to forget it.

Is humanism an answer? Yes, in one way. Since anyone who cares about human beings must be a humanist. But humanism with a capital ‘H’ is an elusive doctrine. If you read the humanists of the Renaissance, the Enlightenment, of Modernity and even up to the present day they occupy all positions from atheist to theist. In other words, it is very hard to say just what humanism is ??" unless you invent a definition by saying what it is not, namely religious. Again, this is what some atheists do. Though to my mind it distorts the humanist tradition and caricatures religious belief.

So what to do? Liberal atheists and believers can make common cause, but not just because they are all liberals. Rather, I think the common cause should rest on opposing what might be called the lust for certainty of the fundamentalist worldview ??" be it religious or scientific. The tradition of scepticism that John represents is the philosophical part of this. But I think we also need its theological equivalent, which is called the apophatic. Apophatic means proceeding by negation. It is a way of approaching what is ultimately unknown by identifying what that unknown cannot be. So theologically, it says God is not mortal (immortal), not visible (invisible). Its spirit is captured in the biblical story of Moses climbing the mountain. As he went up and symbolically got nearer to God, he did not ascend into greater light and clarity, but deeper cloud and unknowing.

If apophaticism sounds esoteric, then actually I think it is something many people intuitively understand. The parish churches of this country may or may not be emptying but the medieval cathedrals are filling up ??" because beautiful music and sublime architecture speaks to people of this ultimate mystery.

The scientific equivalent might be the bestselling popular cosmology books from the likes of Paul Davies and Michael Frayn. They unpack what cosmologists know and at the same time show how this only suggests even more about what they do not know and perhaps never will. Maybe psychoanalysis is another apophatic tradition. What Freud invented was a way of talking about the unknown that is the human individual.

So in a way what the apophatic theologians did was similar to what the Enlightenment philosophers like Hume and Kant did: they identify limits and seek intuitions of what lies beyond. It was called ‘learned ignorance’ by the first Renaissance humanist philosopher, Nicolas of Cusa, and he got the idea from Socrates. Socrates annoyed his fellow citizens in ancient Athens because he showed that the key to wisdom is not how much you know but is understanding the limits of what you know.

So it is this dimension that is needed to combat fundamentalisms, particularly if you want to avoid being forced to become a liberal fundamentalist in response.

The genius of religion ??" at its best ??" is being able to turn this largely intellectual position into a way of life. The tragedy of the present day is that even liberal churches seem to be turning their backs on it. At its core is a sense of the sacred ??" that which is far greater than you and so takes you out of yourself and into the unknown. To put it another way, it is radically agnostic, the phrase I would use to describe my own belief ??" and what I explore in my book.

Radical agnosticism sounds strange but only in a culture dominated by the lust for certainty. And it is key to avoiding what a famous agnostic, Bertrand Russell, called ‘cosmic impiety’ ??" the temptation to treat truth as a means of control, leading to an intoxication with scientific power, and the dismantling of checks on human pride and hubris. Russell called cosmic impiety the greatest danger of his time. It is a danger that shows no sign of passing and I think the new atheists are only deepening it.