The purpose of fanaticism is to take ones cause or belief (whatever it may be) to extremes in order to convince nonbelievers (as well as oneself) that that viewpoint is correct. The very existence of nonbelievers produces self-doubt because, in the eye of the rational mind, if something is a universal truth then all (rational) others will agree. Therefore, either the nonbelievers are not rational (an idea which causes paranoia) or the cause or belief is not a universal truth (an idea which produces self-doubt). But with complete confidence comes a Buddha-like detachment from caring about the idea. Thus, no-one is fanatical about the idea that the sun will rise tomorrow because no-one does not believe the sun will rise tomorrow.