This chapter takes one of the most disturbing contemporary problems arguing that the mind-set of the fundamentalist can be seen in unshakeable beliefs and the conviction of being right. The superego can dictate a violent response to fear and anxiety. Addressing this problem demands understanding and thought. Clinicians have an opportunity to address what we see so that we can begin to modify its effects, helping people to think about their responses to others. This chapter addresses the subject with clinical material and with reference to contemporary writing.