Via the inimitable Mark Steyn, it really doesn't get much better than this:

The fact that Hassan reportedly shouted ["Allahu akbar"] is meant, I suppose, to imply that he was an extremist fanatic. I'm not sure that it does. My understanding is that it's something Arab people often shout before doing something or other. It's used in many different situations.

That's true! Why just the other day, I was grocery shopping, in the dairy section, when a swarthy-looking man screamed "Allahu akbar!" Turned out, on further investigation, he was a Christian Arab who had discovered milk was on sale, and had simply decided, in his joy, to scream an epithet proclaiming the Muslim god to be greater than everything else. We later checked out in the same line, and he yelled it again when they handed him a survey.

Thanks, Michael Tomasky, for sharing from your deep knowledge of "Arab" culture, and dispelling such misconceptions!