Understanding ISIS

My understanding:
Isis puts into force a socioeconomic system with territorial requirements as dictated by the earliest and most cruel Islamic core texts and traditional teachings which are disregarded or even unknown to the vast Muslim community. Isis regards not only non-Muslims, but also mainstream Muslims as apostates needed to be killed. Even arabic countries without the full range of Sharia into force are regarded as betrayors.

The most seriously informative and demanding article I've recently read.

...Muslims can say that slavery is not legitimate now, and that crucifixion is wrong at this historical juncture. Many say precisely this. But they cannot condemn slavery or crucifixion outright without contradicting the Koran and the example of the Prophet. “The only principled ground that the Islamic State’s opponents could take is to say that certain core texts and traditional teachings of Islam are no longer valid,” Bernard Haykel says. That really would be an act of apostasy.

http://www.theatlantic.com/magazine/archive/2015/03/what-isis-really-wants/384980/