Research on why religious deluded would kill in the name of their god.
Hard to research. Interview the terrorists result in this book. Worth get into, I think. Just by how hard it is for us to understand why normal people could turn into terrorists by being brainwashed by religion for years.
All religions are bullshit. Religion present a threat for human. Understanding it would help normal non brainwashed people to deal with this sickness in society.