There's an interesting debate going on at the Guardian about why English-speakers use the word Allah to refer to the Muslim version of God:
There is no logical reason for this. Why use an Arabic word in English-language news reports when there is a perfectly good English word that means exactly the same thing?
Various Arabic words -- jihad and sheikh, for example -- have crept into everyday usage because no precise equivalent exists in English, but "Allah" is not of that type. It is simply the normal word that Arabic speakers use for "God" -- whether they are Muslims or not. Arab Christians worship "Allah" too, and the first verse of the Arabic Bible informs us that "In the beginning Allah created heaven and earth."
And there's a lot more to the argument. Are those who use the word Allah unwittingly "aligning themselves, in effect, with those who view international politics in terms of a clash of civilisations?" Is this an example of "reverse orientalism?" Any thoughts?