That Islam preached terror is a widely known fact.
The Quran's Verses of Violence
The Quran contains at least 109 verses that call Muslims to war with nonbelievers for the sake of Islamic rule. Some are quite graphic, with commands to chop off heads and fingers and kill infidels wherever they may be hiding. Muslims who do not join the fight are called 'hypocrites' and warned that Allah will send them to Hell if they do not join the slaughter.
The proof is the tens of thousands of Islmaic terror attacks all over the world and the zillions of Islamic terror organizations.
ISIS and AQ are following Islam to the letter. The others are hypocrites, trying to pick and choose.
The rapes being committed by the ISIS and other Muslims of non Muslim women is also as per Islam. Youc an find Hadhith supporting rape of women and this has been a common practice of Muslims with the Khailfah getting 20% share of the loot and booty (captured women).
In USA there are several books getting published which are documenting the hate cult in great detail with proof from Quran and Hadhith.
There may be some extremism in other religions, Muslims are the only ones who are practicing it still as they have no scope for changing what they consider "final and perfect" and that leads to them being such fanatics and extremists and terrorists.
Or hypocrites.