“We have not defeated the idea. We do not even understand the idea.”

Major General Michael K. Nagata, the Special Operations commander for the United States in the Middle East commenting on the appeal, popularity and success of ISIS.
Of course not, the civilian commander of all of your forces believes social grievances are the source. You, Genl Nagata cannot even UTTER the name of the idea, for if you do, your career is OVER.
The Atlantic:

The group seized Mosul, Iraq, last June, and already rules an area larger than the United Kingdom
Bin Laden viewed his terrorism as a prologue to a caliphate he did not expect to see in his lifetime. His organization was flexible, operating as a geographically diffuse network of autonomous cells. The Islamic State, by contrast, requires territory to remain legitimate, and a top-down structure to rule it. (Its bureaucracy is divided into civil and military arms, and its territory into provinces.)We are misled in a second way, by a well-intentioned but dishonest campaign to deny the Islamic State’s medieval religious nature.

The most-articulate spokesmen for that position are the Islamic State’s officials and supporters themselves. They refer derisively to “moderns.” In conversation, they insist that they will not—cannot—waver from governing precepts that were embedded in Islam by the Prophet Muhammad and his earliest followers. They often speak in codes and allusions that sound odd or old-fashioned to non-Muslims, but refer to specific traditions and texts of early Islam.

To take one example: In September, Sheikh Abu Muhammad al-Adnani, the Islamic State’s chief spokesman, called on Muslims in Western countries such as France and Canada to find an infidel and “smash his head with a rock,” poison him, run him over with a car, or “destroy his crops.” To Western ears, the biblical-sounding punishments—the stoning and crop destruction—juxtaposed strangely with his more modern-sounding call to vehicular homicide. (As if to show that he could terrorize by imagery alone, Adnani also referred to Secretary of State John Kerry as an “uncircumcised geezer.”)

But Adnani was not merely talking trash. His speech was laced with theological and legal discussion, and his exhortation to attack crops directly echoed orders from Muhammad to leave well water and crops alone—unless the armies of Islam were in a defensive position, in which case Muslims in the lands of kuffar, or infidels, should be unmerciful, and poison away.

The reality is that the Islamic State is Islamic. Very Islamic. Yes, it has attracted psychopaths and adventure seekers, drawn largely from the disaffected populations of the Middle East and Europe. But the religion preached by its most ardent followers derives from coherent and even learned interpretations of Islam.