Far be it from me to in any way defend al Quaeda, but you are mistaken about their aims. Their methods are definitely terrorist, just like McVeigh and Teital and Shamir and numerous others in Israel/Palestine, but they have definite aims, just like those others had. They are not out to kill people just for the fun of it, as you seem to suggest. One aim is to rid Saudi Arabia and other Muslim countries of American influence. Since they operate in Muslim countries, it hardly surprising that most of their victims are Muslim.
Magnitude 4.2 quake strikes near Grand Coulee Dam in Washington (Reuters)
from the article: Alleged Jewish terrorist: I know God is pleased