Though the details differ across the world, no known culture lacks some version of the time-consuming, wealth consuming, hostility provoking rituals, the anti-factual, counter-productive fantasies of religion.

Our leaders have described the recent atrocity with the customary cliche: mindless cowardice. Mindless may be a suitable word for the vandalising of a telephone box. It is not helpful for understanding what hit New York on September 11. Those people were not mindless and they were certainly not cowards. On the contrary, they had sufficiently effective minds braced with an insane courage, and it would pay us mightily to understand where that courage came from. It came from religion.

Are science and religion converging? No. There are modern scientists whose words sound religious but whose beliefs, on close examination, turn out to be identical to those of other scientists who straightforwardly call themselves atheists.

I think there could be a very large number who are creationists by default. Those are the people I want to reach.

Bereavement is terrible, of course. And when somebody you love dies, it's a time for reflection, a time for memory, a time for regret.

As my colleague, the physical chemist Peter Atkins, puts it, we must be equally agnostic about the theory that there is a teapot in orbrit around the planet Pluto. We can't disprove it. But that doesn't mean the theory that there is a teapot is on level terms with the theory that there isn't.

Yesterday's dangerous idea is today's orthodoxy and tomorrow's cliché.