America's leading evolutionary biologist, the late Stephen Jay Goulds, wrote: "Either half my colleagues are enormously stupid, or else the science of Darwinism is fully compatible with religious beliefs - and equally compatible with atheism." To this rejection of the simplistic notion that atheism is the only option for a progressive scientific mind, Professor Richard Dawkins replies (on page 57 of The God Delusion): "I simply do not believe that Gould could possibly have meant much of what he wrote in Rock of Ages." So there we have it. An emotional creedal statement by Prof Dawkins is the only response to reasoned argument based on an observed fact.

It is very comforting, and flattering to the ego, for Muriel Gray and Alistair McBay of the National Secular Society (Letters, August 28) to see themselves as representatives of all that is reasonable, scientific, progressive, intelligent, rational, human and decent. But this is no more than a parade of insufferable arrogance, blind conceit and pride.

Some of the greatest names in science are theists: Joseph Lister, Louis Pasteur, Isaac Newton, Johannes Kepler, Robert Boyle, Michael Faraday, Lord Kelvin, Robert Boyle, Gregor Mendel were all Christian believers. As regards contemporary scientists, believers are strongly over-represented. The sociologist Robert Wuthnow has established that, among academics, scientists were proportionally more likely to be Christians than those in the non-science disciplines. So Muriel Gray and Alistair McBay are being neither rational nor logical in parading their prejudiced conviction that science and religion are incompatible. I would urge them, and readers of The Herald, to ponder the ancient, irrefutable adage, ex nihilo nihil fit - out of nothing comes nothing. Since there are squillions of things in the universe, they logically must have come from something. Or - much more accurately - be coming from something. Creation is taking place every nanosecond.

We manifestly live in a universe of cause and effect; every cause is itself the effect of a previous cause, and so on. Logically, the chain of cause and effect cannot hold itself up, like a cosmic Indian rope trick. It demands a causa non causata, an uncaused cause. That is, a cause which is not itself the effect of a previous cause. This something we call God.

Following Aristotle, St Thomas Aquinas gives five proofs for the existence of God. The first is the argument from causality, to which I have referred. To argue against causality is to argue against all science and rational thought.

The physical singularity of the cosmic event known as Big Bang mirrors and triumphantly vindicates Aquinas's logic.

Brian M Quail, 2 Hyndland Avenue, Glasgow.