How is one excommunicated from Judaism?

Answer 1

Excommunication or Kherem (חרם) is much more seldom in Judaism than in Christianity but it does occur. The most famous examples of Kherem were to Baruch Spinoza in Amsterdam, the Netherlands, and to Rabbi Mordecai Kaplan in New York City.

The person to be excommunicated is summoned before the Chief Rabbis of the jurisdiction in front of the Kahal (קהל), the leaders of the Jewish community. The Chief Rabbi announces the offenses of the person to be excommunicated. In both cases above it was blasphemy. Spinoza was an atheist in the 1600s. Mordecai Kaplan was teaching opinions contrary to Jewish tradition at a Jewish institution. They are asked if they will recant the offenses. If they refuse, a copy of their books or writings is burned to symbolically cleanse the community of their works and the person is stripped of their Jewish rank. The community is told that the offender is "in kherem".

When a person is "in kherem" no member of the Jewish community is allowed to interact with that person in any way. They are not allowed to speak to him, to gesture towards him, conduct any business with him, or to feed him; but they are also forbidden to harm him in any way. If he approaches the Chief Rabbi or the Kahal and recants, even while he is "in kherem", his excommunication is ended and he may rejoin the community. Spinoza never recanted and instead spent the rest of his life with similarly-minded Christian friends. Mordecai Kaplan did not recant either, and he founded an entire new sect of Judaism called Reconstructionist Judaism based on his beliefs. Understandably, many Jews from outside of Reconstructionism see that movement as being outside of Judaism since it was founded on excommunicable philosophies.