Somewhere I have a list of claims a speaker can make that will cause me to instantly suspect the veracity of their argument. Prominent on this list is any thesis that covers over a hundred years: a carefully-written book might be able to connect all the relevant threads: a hour-long talk will not. Similarly, any claim that involves a sufficiently large-scale abstract noun: for example, 'religion.'
Does religion cause violence? Only if you have no idea what qualifies as religion, as apparently many academics who study the question do not. As someone who a. knows a decent amount about the development of theology, Christian and otherwise, in Europe and b. studies the late-medieval and early modern period, when people were constantly fighting about 'religion,' this seems obvious to me. All possible cases are sufficiently complex that I'm not sure I could say what is 'really' driving decision-making: does Ferdinand II, during the Thirty Years War, honestly believe in the correctness of his Jesuit Catholic view and consider converting Protestants and other strands of Catholic to his point of view to be a good thing for their souls? Probably. Is he also a political leader who is attempting to control most of Europe and weaken his adversaries, Protestant or Catholic? Certainly. Which is 'actually' determining his policies? Both, or some combination thereof, which I am not certain one could specify apart from inspection of his soul. So any large-ish claims will be close to unprovable.