Hassan Hassan, on the roots of ISIS ideology that very few care to admit:
Islamic traditions are filled with stories of mercy and tolerance. But it is not enough to tell these stories in isolation from other dark chapters in Islamic history that feed groups such as Isis. Isis uses these stories, combined with ideas and concepts accepted by the mainstream, as part of an ideology and a political project in the making. Muslim clerics speak in the realm of theory; Isis practises through stories and action.
I would add two things. First, there's a problem of context, or lack thereof. These "stories" lack any historical or political context, and are always told to prove the supposed timelessness of the religion. The second thing is historical accuracy. There is little evidence that these stories actually happened, much less date back to the early Islam era.
As an example of clerics engaging in self-serving denial, here is a statement coming from the "moderate" Al-Azhar.
Al-Azhar, Sunni Islam’s most prestigious center of learning, has called for the killing and crucifixion of militants from the Islamic State of Iraq and Syria (ISIS), expressing outrage over their murder of a Jordanian pilot...
Head of al-Azhar, Sheikh Ahmed al-Tayib, expressed his "strong dismay at this cowardly act".
This "requires the punishment mentioned in the Koran for these corrupt oppressors who fight against God and his prophet: killing, crucifixion or chopping of the limbs."
"Islam forbids killing of the innocent human soul... It forbids mutilating the human soul by burning or in any other way even during wars against an enemy that attacks you," Tayib added in a statement.
The contradictions above are telling. If the Qur'an really calls for "killing, crucifixion and chopping" of "corrupt oppressors", can you really fault ISIS for putting that into practice? Can you make an argument against it without examining the text critically and placing it in a proper context?
"Mainstream" Muslim clerics can't have it both ways. They can't reserve brutality for those they deem as oppressors, because that's what got us here in the first place. At the end, they're only justifying the continuance of this ideology, and they're no different from clerics used by ISIS to justify murder and savagery. Note how loud these mainstream clerics became after the immolation of the Jordanian pilot, and how reticent they had been before. It could not be more evident that they are more concerned with furthering the interests of the ruler than inoculating the masses against this brand of savagery.