.
Including under the umbrella of "terrorism" the annual slaughterings of Shiites by Sunnis, and Sunnis by Shiites on their respective holy days, none of which occurs in the real world, and noting the large number of splinter Christian groups... probably 5 within a mile of me right now, with their lack of such assaults on all the other divisions in Christianity, Islam is particularly subject to internal terrorism, in the Stone Age Whogivesacrapistans that have it instead of the rule of secular law, as the real world is blessed with..
The civil authorities don't bomb splinter groups in retaliation for bombings, the secular arm finds the source(s) of the murders and arrests and prosecutes them.
This could be why although there are many Muslims around the world, it's mostly in the religious countries that murder is perfectly OK.