Two very different takes, from two prominent middle east scholars, on the question of how Islamic the Islamic state is -- a debate that I am sure will be with us for a while.
This long piece in The Atlantic quotes Bernard Haykel (who was teaching at NYU when I studied there):
Many mainstream Muslim organizations have gone so far as to say the Islamic State is, in fact, un-Islamic. It is, of course, reassuring to know that the vast majority of Muslims have zero interest in replacing Hollywood movies with public executions as evening entertainment. But Muslims who call the Islamic State un-Islamic are typically, as the Princeton scholar Bernard Haykel, the leading expert on the group’s theology, told me, “embarrassed and politically correct, with a cotton-candy view of their own religion” that neglects “what their religion has historically and legally required.” Many denials of the Islamic State’s religious nature, he said, are rooted in an “interfaith-Christian-nonsense tradition.”
Every academic I asked about the Islamic State’s ideology sent me to Haykel. Of partial Lebanese descent, Haykel grew up in Lebanon and the United States, and when he talks through his Mephistophelian goatee, there is a hint of an unplaceable foreign accent.
According to Haykel, the ranks of the Islamic State are deeply infused with religious vigor. Koranic quotations are ubiquitous. “Even the foot soldiers spout this stuff constantly,” Haykel said. “They mug for their cameras and repeat their basic doctrines in formulaic fashion, and they do it all the time.” He regards the claim that the Islamic State has distorted the texts of Islam as preposterous, sustainable only through willful ignorance. “People want to absolve Islam,” he said. “It’s this ‘Islam is a religion of peace’ mantra. As if there is such a thing as ‘Islam’! It’s what Muslims do, and how they interpret their texts.” Those texts are shared by all Sunni Muslims, not just the Islamic State. “And these guys have just as much legitimacy as anyone else.”
All Muslims acknowledge that Muhammad’s earliest conquests were not tidy affairs, and that the laws of war passed down in the Koran and in the narrations of the Prophet’s rule were calibrated to fit a turbulent and violent time. In Haykel’s estimation, the fighters of the Islamic State are authentic throwbacks to early Islam and are faithfully reproducing its norms of war. This behavior includes a number of practices that modern Muslims tend to prefer not to acknowledge as integral to their sacred texts. “Slavery, crucifixion, and beheadings are not something that freakish [jihadists] are cherry-picking from the medieval tradition,” Haykel said. Islamic State fighters “are smack in the middle of the medieval tradition and are bringing it wholesale into the present day.”
Meanwhile Juan Cole makes the opposite argument in a post entitled "Today's Top 7 Myths about Daesh/ISIL" on his blog:
1. It isn’t possible to determine whether Daesh a mainstream Muslim organization, since Muslim practice varies by time and place. I disagree. There is a center of gravity to any religion such that observers can tell when something is deviant. Aum Shinrikyo isn’t your run of the mill Buddhism, though it probably is on the fringes of the Buddhist tradition (it released sarin gas in the Tokyo subway in 1995). Like Aum Shinrikyo, Daesh is a fringe cult. There is nothing in formal Islam that would authorize summarily executing 21 Christians. The Qur’an says that Christians are closest in love to the Muslims, and that if they have faith and do good works, Christians need have no fear in the afterlife. Christians are people of the book and allowed religious freedom by Islamic law from the earliest times. Muslims haven’t always lived up to this ideal, but Christians were a big part of most Muslim states in the Middle East (in the early Abbasid Empire the Egyptian and Iraqi Christians were the majority). They obviously weren’t being taken out and beheaded on a regular basis. They did gradually largely convert to Islam, but we historians don’t find good evidence that they were coerced into it. Because they paid an extra poll tax, Christians had economic reasons to declare themselves Muslims.
We all know that Kentucky snake handlers are a Christian cult and that snake handling isn’t typical of the Christian tradition. Why pretend that we can’t judge when modern Muslim movements depart so far from the modern mainstream as to be a cult?
2. Daesh fighters are pious. Some may be. But very large numbers are just criminals who mouth pious slogans. The volunteers from other countries often have a gang past. They engage in drug and other smuggling and in human trafficking and delight in mass murder. They are criminals and sociopaths. Lots of religious cults authorize criminality.