Can you give me examples of a branch of ISIS, perhaps even a group of individuals, that do not align its/their reason for being with Islam? The IRA were all catholic paddies and as someone who comes from a catholic paddy family I acknowledge that and will disassociate myself with any of their actions. I won't seek to rationalise, I won't seek reasons, I will just disassociate with the act of murders and will never seek to reason how they might have got to that point or seek to defend them or their supporters ever, at any point, alive or dead.
This is not something I see/hear or believe to be commonly actioned across the Muslim community. I may be wrong of course, but if I knew of a family member about to go off on one off to the police I would go without a second thought. THAT is why people have problems, this isn't the case within vast swathes of what is a very insular community. If you are unable to acknowledge this then any further debate is pointless.