" The zealot may be outwardly motivated by the anticipation of a great reward at the other end—wealth, fame, eternal salvation—but the real recompense is probably the obsession itself. This is no less true for the religious fanatic than for the fanatical pianist or fanatical mountain climber. As a result of his (or her) infatuation, existence overflows with purpose. Ambiguity vanishes from the fanatic’s worldview; a narcissistic sense of self-assurance displaces all doubt. A delicious rage quickens his pulse, fueled by the sins and shortcomings of lesser mortals, who are soiling the world wherever he looks. His perspective narrows until the last remnants of proportion are shed from his life. Through immoderation, he experiences something akin to rapture. "

― Jon Krakauer , Under the Banner of Heaven: A Story of Violent Faith