Well, rather than look at its history, let's look at its foundational principles. What does it teach?
The Koran explicitly authorizes proselityzing at swordpoint, with death for those who refuse. It also specifies the spreading of Islam by military conquest. These commands appear without subsequent mitigating language.
On this basis it becomes clear that there is no equivalency between Christianity and Islam. No reading of Christian texts can amount to a Divine mandate for violence in the service of the Gospel.
Hmmm... it seems to be an easy call to make...
Why should they challenge them. And on what grounds? The murderers are following the religion to the letter.
To challenge them would be like moderate Christians attacking a group of Christians who follow the Ten Commandments on the grounds they are radicals and not with the modern world. - Tom