Terrorist groups like the Islamic State and regimes like Nazi Germany often justify their crimes through their ideology. Did they really believe they did the right thing or was ideology used as an excuse to commit evil? In this episode, we discuss the role of ideology in mass atrocities together with Dr. Pieter Nanninga from the University of Groningen. He is an expert on terrorism and studied, among other things, short films that suicide terrorists made prior to their attacks.