To extend some of the replies above, how often do you hear some liberal commentator say that "real Christian fundamentalists aren't mean-spirited"? Or even "Not all pro-lifer protesters believe in shooting abortionists"?
Two or three whackos kill abortionists, and the media have spent twenty years smearing the pro-life movement. Millions of Muslims dance and cheer when the Trade Towers collapse, and the media will no doubt spend twenty more years explaining why they are all really innocent victims of American imperialism.
I will give you a two letter explanation: PC.