Both Mordecai Kaplan, the rationalist, and Abraham Joshua Heschel, the mystic, believed that Judaism compels us to make the world a better place. Kaplan was committed to the ethical practice adopted by the Jewish People throughout our history, while Heschel’s social activism was motivated by a prophetic imperative: transforming God’s will into action. Louis Finkelstein, the influential Chancellor of JTS, also stressed the importance of action, recognizing the unique role of the Jewish community in his time and place.

Further reading
Abraham Joshua Heschel, God in Search of Man, 3-4, 167, 184-199
Louis Finkelstein, “Tradition in the Making,” “The Things that Unite Us,” in Waxman, Tradition and Change, 187-197, 313-324