The question is, why haven't muslims risen up and denounced such action. Because Christianity and a God none other than theirs is the enemy. American, England are not muslim nations and therefore are enemies.
The whole purpose of islam is to subjugate everyone to their religion by force.
Look at their history.
You could say the same thing about liberals, but rounding them up and jailing them isn't what America is about.
I am sorry, but can you name an prostelitizing religion that hasn't grown through conquering other people and used passages in the religious text to justify what were ultimately political decisions?
Moreover, other than the last 50 years of "relative" peace, man has been in a constant state of war almost everywhere in the world. Religion always came into to play when the people fighting had different ones.