“The President of the United States has claimed, on more than one occasion, to be in a dialogue with God. If he said that he was talking to God through his hairdryer, this would precipitate a national emergency. I fail to see how the addition of a hairdryer makes the claim any more ludicrous or offensive.”
- Sam Harris, Letter to a Christian Nation

The September 11th attacks were essentially religious acts. Whatever the hijackers' political or social motivations, they believed they were doing God's work and would be justly rewarded in the afterlife. It was religious faith that ultimately turned them into killing machines.

Worshipping deities seems an irrational and wasteful habit, yet it is found in all cultures. Why is religion so widespread? Wouldn't natural selection have got rid of religious tendencies if religion were clearly bad for humans after all?

Any positive aspects of religion can be replaced by equally beneficial non-religious substitutes. For some people, consolation and inspiration are genuine benefits of religion, but these functions can be fulfilled by other means. Contemplation of the natural world does the job - consider the perspective-altering discoveries of modern physics. But only a minority find as much consolation in quantum physics as in the prospect of reuniting with their dearly departed in heaven.

Religion can be thought of as a by-product of mental abilities that evolved for other purposes. Children are “programmed” to believe anything their parents tell them, which is quite sensible in light of all the useful information parents can share. But this system is vulnerable to becoming a conduit for worthless information that is passed on for no other reason than tradition.

In practice, religion is not a legitimate source of morality. If it were, Jews would still be executing those who work on the Sabbath. Where morality actually does come from is less clear. The source is probably a combination of genetic instincts, which evolved because morals allowed humans to benefit more efficiently from co-operation, and a cultural Zeitgeist.

Today, atheists are in the same situation as homosexuals were 50 years ago: stigmatised and unelectable to public office (in America, at least). We can dream of a day when atheists are as well organised and influential as Christian conservatives have become.