The following is an excerpt from a fine article, What ISIS Really Wants, in The Atlantic by Graeme Wood dated March 2015. I highly recommend you go read the entire article, share it with your friends and keep a copy for future reference.
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.
Virtually every major decision and law promulgated by the Islamic State adheres to what it calls, in its press and pronouncements, and on its billboards, license plates, stationery, and coins, “the Prophetic methodology,” which means following the prophecy and example of Muhammad, in punctilious detail. Muslims can reject the Islamic State; nearly all do. But pretending that it isn’t actually a religious, millenarian group, with theology that must be understood to be combatted, has already led the United States to underestimate it and back foolish schemes to counter it. We’ll need to get acquainted with the Islamic State’s intellectual genealogy if we are to react in a way that will not strengthen it, but instead help it self-immolate in its own excessive zeal.
Control of territory is an essential precondition for the Islamic State’s authority in the eyes of its supporters. This map, adapted from the work of the Institute for the Study of War, shows the territory under the caliphate’s control as of January 15, along with areas it has attacked. Where it holds power, the state collects taxes, regulates prices, operates courts, and administers services ranging from health care and education to telecommunications.
In November, the Islamic State released an infomercial-like video tracing its origins to bin Laden. It acknowledged Abu Musa’b al Zarqawi, the brutal head of al‑Qaeda in Iraq from roughly 2003 until his killing in 2006, as a more immediate progenitor, followed sequentially by two other guerrilla leaders before Baghdadi, the caliph. Notably unmentioned: bin Laden’s successor, Ayman al Zawahiri, the owlish Egyptian eye surgeon who currently heads al‑Qaeda. Zawahiri has not pledged allegiance to Baghdadi, and he is increasingly hated by his fellow jihadists. His isolation is not helped by his lack of charisma; in videos he comes across as squinty and annoyed. But the split between al-Qaeda and the Islamic State has been long in the making, and begins to explain, at least in part, the outsize bloodlust of the latter.
Zawahiri’s companion in isolation is a Jordanian cleric named Abu Muhammad al Maqdisi, 55, who has a fair claim to being al-Qaeda’s intellectual architect and the most important jihadist unknown to the average American newspaper reader. On most matters of doctrine, Maqdisi and the Islamic State agree. Both are closely identified with the jihadist wing of a branch of Sunnism called Salafism, after the Arabic al salaf al salih, the “pious forefathers.” These forefathers are the Prophet himself and his earliest adherents, whom Salafis honor and emulate as the models for all behavior, including warfare, couture, family life, even dentistry.
The United States is handicapped by President Barack Hussein Obama who refuses to admit ISIS is Islamic, the stupidity is impossible to understand ... Except for the belief that his sympathies lie with them and cares nothing for the Christians and moderates that are being slaughtered.
Following takfiri doctrine, the Islamic State is committed to purifying the world by killing vast numbers of people. The lack of objective reporting from its territory makes the true extent of the slaughter unknowable, but social-media posts from the region suggest that individual executions happen more or less continually, and mass executions every few weeks.
Centuries have passed since the wars of religion ceased in Europe, and since men stopped dying in large numbers because of arcane theological disputes. Hence, perhaps, the incredulity and denial with which Westerners have greeted news of the theology and practices of the Islamic State. Many refuse to believe that this group is as devout as it claims to be, or as backward-looking or apocalyptic as its actions and statements suggest.