most Muslims who commit terrorist attacks and join terrorist groups have hardly any background in religion or have little knowledge in religious texts at all. In fact, evidence suggests that in some areas the more background in Islam you have the less likely you are to commit a terrorist attack. People don't join terrorist groups to become religious scholars they do so to become holy warriors. The main factors that make people join terrorist groups are a sense of brotherhood, camaraderie and to give themselves meaning, for glory. Young disaffected youth is a prime recruiting target for terrorist groups. There is most certainly a violent current in Islam at the moment but Here is some background info if you want to learn more about it.
https://www.nybooks.com/daily/2015/11/16/paris-attacks-isis-strategy-chaos/
https://www.amazon.com/gp/product/B003VIWNNA/ref=dbs_a_def_rwt_hsch_vapi_taft_p1_i1
https://www.nybooks.com/daily/2016/07/16/nice-attack-isis-durability-of-chaos/
https://www.nybooks.com/daily/2017/10/19/isis-after-the-caliphate/