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They Burned His Prayer Book. He Changed American Judaism.

8/30/2026 • 5,878 views

On June 12, 1945, five weeks after Germany surrendered, more than two hundred Orthodox rabbis gathered at the Hotel McAlpin in Manhattan to excommunicate Mordecai Kaplan. Then a copy of his prayer book was burned. Kaplan was not a Reform rabbi, a secularist, or an outsider. He held Orthodox ordination, kept a kosher home, taught at the Jewish Theological Seminary, and had staged the first bat mitzvah in America for his own daughter. That was exactly what made him dangerous. Kaplan argued that Judaism was not only a religion but an evolving civilization: language, peoplehood, land, culture, law, memory, and prayer. He stopped believing in a supernatural God who commands and intervenes, and instead described God as a process, "the power that makes for salvation." Then he did the most dangerous thing a Jewish thinker can do: he put the theology into the prayer book. The 1945 Sabbath Prayer Book removed chosenness, the personal Messiah, divine retribution, supernatural intervention, and the restoration of Temple sacrifices. Agudat HaRabbanim answered with a herem. Whether the burning itself was planned is still disputed. The organization later insisted it was not; its own journal printed the halakhic justification. Nobody knows who struck the match. The excommunication failed. Kaplan stayed at the Seminary for eighteen more years. Reconstructionism became America's fourth Jewish denomination. And many of the edits that once made his prayer book untouchable now read like the defaults of liberal Jewish liturgy.