Islam might be the only [major] religion to be considered as still violently crusading or at least excessively oppressive, I'd guess. And because it's largely accurate to call it such.
Oh, I don't think anybody's disputing the fact that ISIS and co. are Islamic extremists, and for a matter of fact, that Islam has the biggest terrorist threat of any religion. But why people care so much over labeling them as Islamic is what I want to know.
I think that by declining to explicitly call them Islam
ic (rather than Islam
ist), you would be implying that the bolded part is not necessarily true.