One could easily argue that Catholic extremism led to WWII fascism. It's not so far away in the past as you think. There's plenty of rampaging christians in Nigeria up to their necks in sectarian bloodshed as well. Same with Lebanon.
No religion has left their violence in the past, they have a book, hadtih/scrolls and vickers/mullahs which tells them they have a divine right to certain things like violent retribution for blasphemy or "blood atonement" and land titles, so violence will continue forever. Even buddhists are rampaging in Myanmar with machetes butchering up a sectarian storm.
I'm not going to argue pre-WWII Catholicism, it's about as relevant as eugenics and Aryanism (the west has changed a lot), but the violent Christians / Buddhists you are pointing out seem to be in response to violence from some members of Islam, so it's basically just tribal violence.
And Buddhists don't have such a book, so I'm not sure what you're actually arguing here other than that religious fundamentalism is bad. Most religious people in the west already believe that (unfortunately not all of them).
No religion has left their violence in the past, they have a book, hadtih/scrolls and vickers/mullahs which tells them they have a divine right to certain things like violent retribution for blasphemy or "blood atonement" and land titles, so violence will continue forever. Even buddhists are rampaging in Myanmar with machetes butchering up a sectarian storm.