Where will this stop?

Wikipedia

How many hundred kilometres is it from Raqqa to Masada? Less than six hundred. Today it's the Tomb of Jonah, the Shrine of Seth. Is it conceivable that at some future date ISIS takes another few hundred square kilometres on the back of local strife and threatens Bethlehem's Church of the Nativity, The Holy Sepulchre and other precious monuments not so far from where they are now? Israel is not exactly doing a great job at present of showing it can live alongside its Sunni neighbours and working very hard to earn a generation's resentment from much of the Moslem world. Let us remember that ISIS is also ISIL, and where that "Levant" is.

An ethnic map of the Levant (A World in Crisis.org)