Debate: Islamic Terrorism or Extremism with no connection to Islam?

In the last couple of days, folks are having a conversation about radical groups professing their Islamic faith.
A large number of Muslim (let’s call them mainstream) believes that the terrorist group like ISIS/ISIL has nothing to do with Islam. These extremists may claim to be Muslims but their actions show otherwise.

"There's no such thing as radical Islam," Awad said. "There's no violent extremist ideology within Islam. Islam is one. Some people become extremists, but it's not because of the religion — it's because of themselves as individuals. I think people get entangled in terminology when, in fact, we are dealing with criminality. Criminals are criminals." [1]

Obviously the terrorist group ISIS/ISIL would disagree. According to ISIS/ISIL, most of the mainstreams Muslim are not really Islamic based to their own interpretation and legal judgment (theology). Only the ones who join their cause and accept their hardcore version of Islam can truly be considered a true believer of Islam.

The main dilemma is that both sides think they have the correct version of Islam worthy of representing all Muslim while the other sides are misguided.

Yesterday, I was watching this discussion on TV [2]. David Brooks get invited to a lot of these programs. You cannot always believe what he says because a lot of time his opinions are flatly wrong, but sometimes he makes an interesting point, like yesterday

DAVID BROOKS: Well, are we allowed to called the Islamic State Islamic?

They are. In some sense, it’s a stupid debate, because is it true Islam, is it perverted Islam? The fact is, religion is all interpretation. God doesn’t come down here and tell us exactly what he means. We have interpretations within Christianity, within Judaism and within Islam. If you call yourself a Muslim, you’re a Muslim.

They have different interpretations, but it’s all interpretations. So, one is a perverted or a sick form of Islam. A lot of people fortunately have a much more peaceful form of Islam, but it’s all an interpretation of a faith. What’s the real one? It’s all a matter of interpretation.

I think they should probably call it Islamic extremism. It is Islamic extremism. The second, I think, and more important issue is how we diagnose the problem. And there are three elements to this sort of terrorism, as we just saw in the segment about that Egyptian young man.

First, there’s economic and political dysfunction. So that young man wanted to be a personal trainer and he couldn’t. So he was alienated from that and marginalized from society.

But, second, there’s a spiritual ardor. A guy wants to be a hero. The guy wants to be seen as strong and a hero, like that young man.

And, third, there’s theological conviction. And Islamic State has theology to it, real, substantive theology. We’re comfortable talking about the economics and the politics because we live in a secular society and we’re comfortable talking about that stuff.
But if we don’t talk about the spiritual call that they feel and the theological content, then we’re missing the core of the thing. And if we’re going to fight it, you can’t just say we’re going to give you a higher standard of living. You don’t need to go to the Islamic State. That isn’t going to work. You have to have a spiritual, better alternative. [2]

References
[1] http://www.npr.org/2015/02/20/387611455/more-muslim-groups-voice-willingness-to-combat-extremism-in-their-faith
[2] http://www.pbs.org/newshour/bb/shields-brooks-fighting-islamic-extremism-giuliani-obama/