Important questions
I have a theory about what ISIS might be trying to do: McFly's ISIS TheoryTM
I don't think they're really trying to start a shooting war with, basically, the entire planet. Rather, I think they're trying to create an atmosphere of mutual hatred between the Muslim and non-Muslim world. Once they've isolated Islam, it'll be easier for them to shape it the way they want it--free of the influence of western and non-Muslim ideas.
As you say, they've alienated pretty much every major player, including the US, Russia, China, Japan and most if not all of Europe. Either they're simply insane, or they're looking for a specific outcome.