A religious fanatic is someone who is extremely devoted to their religion and often holds extreme views. A ZEALOT is a term used to describe a religious fanatic, and it is derived from the Greek word 'ZEAL' which means enthusiasm or passion. A religious fanatic is often characterized by their intense devotion to their faith and their willingness to go to extreme lengths to defend it. They may also be intolerant of other beliefs and may even resort to violence in order to protect their own.