“The fiercest fanatics are often selfish people who were forced, by innate shortcomings or external circumstances, to lose faith in their own selves. They separate the excellent instrument of their selfishness from their ineffectual selves and attach it to the service of some holy cause.” (Eric Hoffer, The True Believer: Thoughts on the Nature of Mass Movements)
Related: Kierkegaard’s speech in praise of Abraham.