My point was that there was an essential similarity between the ethical position of Bin Laden and Bush (and those who agree with them). Both evidently believe that they are combatting something supremely evil, and that this justifies actions which mean the death of many thousands of innocent people.   

I think that the general view of people who believe this kind of thing is that, while killing thousands of innocent people is indeed evil, it is a necessary and therefore a justified evil, rather than a good thing in itself.

I agree that in a real sense "evil is in the eye of the beholder" - people who are involved too closely in actions which are profoundly evil, such as September 11, are virtually certain to have found ways of justifying these to themselves. Only if you are "a beholder" - including victims in that term - can you see such actions for what they really are.

In order to understand an adversary, which is important if you wish to anticipate what they might do, and how they might react, it is necessary to recognise that in their eyes what they do is either good or else a necessary evil.