... and you can tell by the targets they consistently choose.
To be Muslim is to do what Mohammed told you to do. Mohammed told you to slay the infidels, not knock out their power grids, blow up railroad bridges, wreck their water system or take down the Internet. It's no good to fire a few, damaging rounds into power relay station, destroying transformers and causing surges and shorts across the system, you need to kill infidels.
This is why Germany has a couple of train stations on lock down and not their entire infrastructure.
Yes, ISIS is Islamic and it's a good thing, too. If they weren't, we'd really be screwed.