Rabbi Mordecai Kaplan redefined Judaism as an “evolving religious civilization” in need of reconstruction for the 20th century. He emphasized Jewish peoplehood, in all its complexity and diversity, as the central pillar of Jewish life and culture, and as the means of survival for Judaism in modern society. From the Bat Mitzvah to the Jewish community center, Kaplan’s ideas have since permeated into nearly all aspects of American Jewish life.