Religion changes, for people, the definition of good. Atheists and humanists tend to define good and bad deeds in terms of the welfare and suffering of others. Murder, torture, and cruelty are bad because they cause people to suffer. Most religious people think them bad, too, but some religions (for example the religion of the Taliban) sanction all of them under some circumstances. For non-religious people, the behavior of consenting adults in a private bedroom is the business of nobody else, and is not bad unless it causes suffering – for example by breaking up a happy family. But many religions arrogate to themselves the right to decide that certain kinds of sexual behavior, even if they do no harm to anyone, are wrong.

The actions of the Taliban, their vile bullying of women, their sanctimonious hatred of all that might lead to enjoyment, their violence, their ignorant bigotry, their hatred of education, their cruelty, seem to me to be as close to pure evil as anything I can imagine. Yet, by the lights of their own religion they are supremely righteous – really good people.

The nineteen men of 9/11, having washed, perfumed themselves and shaved their whole bodies in preparation for the martyr’s paradise, believed they were performing the highest religious duty. By the lights of their religion they were as good as it is possible to be. They were not poor, downtrodden, oppressed or psychotic; they were well educated, sane and well balanced, and, as they thought, supremely good. But they were religious, and that provided all the justification they needed to murder and destroy. Their madrassas and their mullahs had given them good reason to think they were on a fast track to paradise.

Polls suggest that 13% of British Muslims regard the 7/7 London bombers as blessed martyrs. Neighbors and friends expressed bewilderment that such nice, gentle, kind, youth-clubbing, cricket-loving young men could do such terrible things. But once you understand what they truly and sincerely believed – that it was Allah’s will that they blow up buses and subways – it becomes all too easy to understand.

It is easy for religious faith, even if it is irrational in itself, to lead a sane and decent person, by rational, logical steps, to do terrible things. There is a logical path from religious faith to evil deeds. There is no logical path from atheism to evil deeds. Of course, many evil deeds are done by individuals who happen to be atheists. But it can never be rational to say that, because of my nonbelief in religion, it would be good to be cruel, to murder, to oppress women, or to perpetrate any of the evils on the Hitchens list.

The following quotation from the Nobel prize winning physicist Steven Weinberg has become well known, but it is so devastatingly true that it is worth quoting again and again: “With or without [religion] you’d have good people doing good things and evil people doing evil things. But for good people to do evil things, it takes religion.”