Faizan your suggestion that religion is not bad, may be true. But to my knowledge, may be its limited but polygamy is encouraged by Islam is it good, Islam dosent give recognition to any religion isnt it potent enough to make Islam followers violent. In fact root cause of these terrorism is due to non tolerance of Islam and no recognition of other religions. Now why it is followed worl wide, read Islamic history you will know how many people followed out of will and how many were forced. Simple example Aurnagjeb had "Jajiya Tax" imposed on non muslims. The very foundation is wrong, the concept of one GOD thats Allah is the root of the violence worldwide. Hindu;s have a history of tolerance but Islamic extremism is leading to fanaticism in some Hindu's also to save themselves.
