Actually that's not entirely correct. ISIS occupies and holds territory including cities that they defend. Their government runs the civil affairs in these areas as well. They also fight like people use to fight including killing the men and reorienting the women and children to their way of life. I doubt if there are "molesting" forces within their ranks.
The West has to get away from the idea that this is a religious war. This is, at least with ISIS, a territorial war and we should treat it as such. They have begun to create a territorial caliphate, similar to the Ottoman Empire, just smaller. Their attacks in lands like America and France are their way of attacking their enemy. They don't have long range bombers and fighter aircraft as we do. This is not terror or a criminal action on their part but rather----war! Until we understand that, we won't do the right thing to defeat them.