You Already Knew This
Somehow, we all knew this. Deep inside. But too much of bad people doing bad things in the name of religion would tarnish the religion eventually. That, plus the propaganda deliberately aimed to achieve the same objective. Why is it that when someone does something in the name of a prominent figure, we would all first verify with that figure to determine the truth. But when someone does something bad in the name of Islam, none of those who immediately blame Islam actually take some effort to study and verify it with Islam?