When trying to reach reasoned and compassionate judgments, religion is frequently a source of confusion rather than light, argues Oliver Kamm.

The secular mind is better equipped than religion to reach reasoned and compassionate judgments. That was the argument of Ian McEwan at the Oxford Literary Festival this week. It should not be controversial. Religious belief resolves no moral problem and yields no knowledge. On the contrary, much suffering is caused by people who believe they know the will of God and have a duty to enforce it.

Of course, not all religions are like that. The Unitarians are different from the Church of Scientology. Liberal Judaism is not the creed of the messianic settlers on the West Bank. The ideas of Spinoza and Bertrand Russell appeal to me, but I'd settle for the victory of moderate forms of religion, which accept science and pluralism, over absolutist ones.

Despite their outward differences, however, religions typically have a lethal assumption in common: that faith is a virtue. How often have you heard someone described as a person of deep religious convictions and for this to be meant as a criticism?

It ought to be, and McEwan does public debate a service in suggesting it. Religious affiliation is less divisive in Western societies than it was 300 years ago. That's not because believers have lately had a divine revelation about the need to live in peace with others and respect their human rights. It's because liberal, secular values have tamed religion as a source of conflict. It isn't the Bible or the Koran that has made Western societies democratic and tolerant. It's the idea, encapsulated in Thomas Jefferson's Virginia Statute for Religious Freedom, that what people believe is irrelevant to public office. As the Protestant theologian Reinhold Niebuhr wrote: "All men are naturally inclined to obscure the morally ambiguous element in their political cause by investing it with religious sanctity. This is why religion is more frequently a source of confusion than of light in the political realm."

The decline of religious observance in modern democratic societies is an important civilising influence. Even moderate forms of religion don't regard criticism as a way of social and personal betterment. Instead, they try to accommodate traditional (and often ancient) religious doctrines to new discoveries. And that's religion at its most benign. The more potent form of faith seeks to justify doctrines and practices that defy rationality and compassion. Not all inhumanity is due to religion but religious obscurantism, even by mainstream churches, coexists with inhumane conclusions. Refuse abortion, even in the case of rape, incest or severe foetal abnormality? Tell devoted homosexual couples that their selfless love and care for each other is sinful? It takes religious dogma to do that.

In the Book of Judges, Jephthah vows to sacrifice "whatsoever cometh forth of the doors of my house" on his return if God will grant him victory over the Ammonites. He, at least, has the decency to tear his clothes when this turns out to be his daughter. In Byron's telling, she urges Jephthah to "forget not I smiled as I died". That imperishable image of fanaticism is the fruit of faith. Civilisation depends on overcoming it.

Oliver Kamm is a leader writer and columnist for The Times. This article was originally published in The Times and is reproduced here with kind permission. The views expressed are those of the author and do not necessarily represent the views of the NSS.