“The fanatic is perpetually incomplete and insecure. He cannot generate self-assurance out of his individual resources—out of his rejected self—but finds it only by clinging passionately to whatever support he happens to embrace. This passionate attachment is the essence of his blind devotion and religiosity, and he sees in it the source of all virtue and strength. Though his single-minded dedication is a holding on for dear life, he easily sees himself as the supporter and defender of the holy cause to which he clings. And he is ready to sacrifice his life to demonstrate to himself and others that such indeed is his role. He sacrifices his life to prove his worth.
It goes without saying that the fanatic is convinced that the cause he holds on to is monolithic and eternal—a rock of ages. Still, his sense of security is derived from his passionate attachment and not from the excellence of his cause. The fanatic is not really a stickler to principle. He embraces a cause not primarily because of its justness and holiness but because of his desperate need for something to hold on to. Often, indeed, it is his need for passionate attachment which turns every cause he embraces into a holy cause.
The fanatic cannot be weaned away from his cause by an appeal to his reason or moral sense. He fears compromise and cannot be persuaded to qualify the certitude and righteousness of his holy cause. But he finds no difficulty in swinging suddenly and wildly from one holy cause to another. He cannot be convinced but only converted. His passionate attachment is more vital than the quality of the cause to which he is attached.

Though they seem to be at opposite poles, fanatics of all kinds are actually crowded together at one end. It is the fanatic and the moderate who are poles apart and never meet. The fanatics of various hues eye each other with suspicion and are ready to fly at each other’s throat. But they are neighbors and almost of one family. They hate each other with the hatred of brothers. They are as far apart and close together as Saul and Paul. And it is easier for a fanatic Communist to be converted to fascism, chauvinism or Catholicism than to become a sober liberal.”