Yes, Christianity once birthed something as awful as ISIS: the Crusades. Just go read it.
Cultural ignoramuses portrayed President Obama’s references to the Crusades and the Inquisition at the recent National Prayer Breakfast as an excuse for Islamic terrorism, but the president’s allusions could and should have been used as an opportunity to reflect on the special damage inflicted in many historical contexts by warriors seeking conquest in the name of their god.
That sound you hear is a zillion rightwing religious heads exploding. Sweet, isn't it?