Why Islam has been labeled as terrorist?

Why Islam has been wrongly labeled as terrorist religion since in all religion there are extremist and they are not label as their religion terrorist? If the terrorist is a muslim then he/she is a terorrist not Islamic terrorist. Why must put the Islam infront of the terrorist. My friend who studying at UK has been beaten nearly to death by a group of Cristian just because he just come out from a mosque. Is'nt that not a terrorist act. Terrorist is whoever has commit terror to the others. So who are the terrorist here. Stop blaming on religion. This is an act of person or people. Not religion. They just use religion as their cause.