We must not allow our desire for revenge lower our moral standards

Let me mention another date: July 20, 1944. It probably doesn't ring a bell with many people, but it was the day of the von Stauffenberg plot, sometimes known as the Generals' Plot, to kill Hitler. It failed, and the conspirators were hanged slowly with piano wire (Hitler's favourite entertainment in the following months was to watch the film of the executions over and over again).

Many reasons have been given for this plot: the generals' knowledge that the Germans were going to be defeated, so they attempted to make themselves less culpable; their universal hatred of this working-class upstart Hitler; even a genuine attempt to stop the atrocities against the Jews.

What is more important in the wider context is to realise that among the conspirators was a gentle German pastor and academic, Dietrich Bonhoeffer, a pacifist and teacher of ethics, who gradually came to the realisation that he could no longer stand by and do nothing about the evils of the Nazi regime.

"We have been silent witnesses of evil deeds," he said. "We have learnt the art of equivocation and pretence." And he came to see that the purpose of ethics was not as simple as just doing good but to change the world for the better, which might mean choosing between two evils.

So his involvement in the assassination plot came about gradually, when he was faced with an evil that was outside his normal frame of reference.

Although he couldn't be directly involved, he helped make it possible for others to carry out the attempt for, in the words of theologian Larry Rusmussen, "to want something done, but to refuse to take part in doing it, is a parasitic position".

Bonhoeffer's world was changed by Hitler, forcing him to rethink his former pacifist position, and to realise that pacifism is not necessarily the same as passivity.

The terrorist attacks of September 11 changed our world, and many people in the West are rethinking their attitudes, too.

But, like Bonhoeffer, what we must realise is that taking steps to defend the world against evil is not the same as taking revenge against the perpetrators of evil deeds.

To call for the death penalty for the Bali bombers, say, is to reduce ourselves to their level, as despicable a position as gloating over the bodies of the sons of Saddam Hussein.

Bonhoeffer believed that Hitler had to be exterminated, even if it meant killing other people as well, because it was a lesser evil that would bring about a greater good. But if he had not been executed just before the war ended, I wonder whether he would have called for the death penalty for the perpetrators of the Nazi atrocities at the subsequent Nuremberg trials?

I suspect that revenge never became part of his ethical belief system.