Religious fanaticism has manifested itself in Christian religion amid the action of religious entities whose members have not accepted individuals who have not mastered their doctrines and fanatical goals. The phenomenon was identified only with a part of the Christian confession, indifferent of the rite: Catholic, Protestant or Orthodox. The roots of unaltered fanaticism over the past millennium are clear and edifying, in the sense that all fanatics believed to fulfill the will of divinity. They also thought it was their duty to modify society according to their own confession, demonstrating special violence to achieve their goals. The partial or total destabilization of the states in which they appeared and manifested was common, and the killing of thousands of people to set up communities or even theocrats became normal. In the following I intend to point out these references from the medieval - contemporary perspective and the measures of the authorities to prevent attacks on individual life and integrity and on national or international security.