You need to slightly modify your post. There are different types of terrorism, such as religious terrorism, drug-related terrorism, communist terror.etc. There are non-Muslims involved in some types of terror, such as the NDFP / NPA of the Philippines. But 99% of the terrorism motivated by religion are committed by Muslims.
I agree. Yes most religious terrorism are committed by Muslims which can be traced form ita history if you try to research it. Moreover, this movement is not really for their religion but rather their drive to power in uniting every Muslim ib the world as a caliphate and rule over them as caliph which are connected through the death of Muhammad and the greed of power which splits Islam into a lot of different factions.
FYI we studied the history of Islam way back when we were still making our term paper regarding the contemporary issue we continue to face particularly the ISIS or also known as ISIL.