Beheadings. Torture. Kidnappings. Execution-style murders. Unspeakable acts of barbarism. Rape as a weapon of war.

Today’s headlines are filled with atrocities, many of them associated with radical Islam. For example, my initial reaction is that the masked faces behind ISIS are clearly the “bad guys”and people in the West are the “good guys.” And then something mind boggling like the execution-style murders of three Muslims in Chapel Hill, North Carolina happens. It can get really confusing.

Examples of violence in history across the religious spectrum are invoked by journalists and political leaders in order to give us perspective. For many, the actions associated with extreme Islamic jihad are comparable to the aggressive militancy of the Crusades waged by Western Europeans in the Middle East during the medieval era. Countless readers of history, both from Christian and Islamic backgrounds, accept the narrative made famous by 20th century medieval historian Sir Steven Runciman that the Crusades remain the classic example of unprovoked, religious intolerance and unbridled fanaticism.

So, is this a fair comparison? Did the offensive actions of those medieval Crusaders provoke modern day extreme Islamic jihad? Or were the Crusades primarily intended to be an act of defense against the juggernaut advance of militant Islam over the preceding centuries?

Let’s face it. History can get really complicated, particularly when talking about violence, especially religiously motivated violence. How do we sort these things out?

Thomas F. Madden is a professor of medieval history at Saint Louis University. He is one of the leading academic historians on the Crusades. Many of the things Madden talks about regarding common misunderstandings of the Crusades may surprise you. Madden gave the following talk before a Catholic audience (here is a summary of his main points):