Reprinted from The Jewish Religion: A Companion, published by Oxford University Press.
Fanaticism is excess of zeal in religious matters, especially when directed against others. Judaism, like most other religions, has had to face the problem of how to achieve a balance between complete, uncompromising loyalty, pursued with enthusiasm and utter conviction, and unbridled zeal, the possessor of which ignores some of the values of the religion itself. The problem is to distinguish between religious zeal and fanaticism.
The scriptural prototype of the zealot is Phinehas who slays Zimri, the prince of Israel, and the Moabite woman with whom Zimri had intercourse in the presence of all the people (Numbers 25:1-15). Building on this scriptural passage, the Talmudic rabbis remark that "Zealots slay one who has intercourse with a Syrian woman" but this is "a law that must not be taught."
That is to say, Phinehas was not guilty of murder but had he asked Moses beforehand for a statement of the law, Moses would have been obliged to reply that it is an act of murder. Indeed, the Rabbis go on to say, if Zimri had defended himself by slaying Phinehas, he would have acted in self-defense and murder, since Phinehas had designs on Zimri’s life (Sanhedrin 8Ia-82b).
Scholars are surely correct in hearing in all this echoes of the discussions around the activities of the Zealots during the war with Rome in 66-72 CE, towards whom the later rabbis had an ambivalent attitude.
In the later tradition, the Talmudic passage was used to convey the principle that if a man has to ask whether his fanaticism is lawful; if, that is, he has to weigh up his actions beforehand and is sufficiently calm to do this; then his act is not carried out by an ungovernable religious impulse and he is to be blamed for his fanaticism. The idea appears to be that fanaticism, especially when it flies in the teeth of Jewish values, is to be rejected and can only be tolerated, but not necessarily admired, when completely spontaneous.
There have been Jews throughout the ages who took pride in their fanaticism. But against such fanatics the verse was generally applied: "Be not righteous overmuch (Ecclesiastes 7:16)." It is said that a man complained to the Hasidic master, Menahem Mendel of Kotsk, that people called him a fanatic, saying. "Why am I called a fanatic and not a Jew zealous for his religion?" The Kotsker replied: "A fanatic is one who turns a minor issue into a major one."
Pronounced: khah-SID-ik, Origin: Hebrew, a stream within ultra-Orthodox Judaism that grew out of an 18th-century mystical revival movement.