Yes, they epitomise evil. ISIS are fundamentalist muslims. They want the restoration of the lost Caliphate and they want it at any cost. I really can't see the US not stepping in. They did it before when the Kurds were fleeing from Saddam back in '91 and I'm pretty sure we'll see the US intervene here too. I'm sure that it won' just be a humanitarian effort either, I think we'll see the US target ISIS militarily.
Why not let them get on with it? Sever ties with the Muslim countries like that and let them crack on with murdering one another. Why should we be world police?
Ohwait, that's right, the oil.