Franz Rosenzweig was born in Kassel, Germany to a minimally observant Jewish family. His education was primarily secular, studying history and philosophy at the universities of Göttingen, Munich, and Freiburg.
While researching his doctoral dissertation on the 19th-century German philosopher Georg Wilhelm Friedrich Hegel, Rosenzweig reacted against Hegel's idealism and favored an existential approach.
Rosenzweig, for a time, considered conversion to Christianity, but in 1913, he turned to Jewish philosophy. His letters to his friend, Eugen Rosenstock-Huessy, whom he had nearly followed into Christianity, have been published as Judaism Despite Christianity. He became a philosopher and student of Hermann Cohen.
Rozensweig's major work, Star of Redemption, is his new philosophy in which he portrays the relationships between God, humanity and world as they are connected by creation, revelation and redemption. He criticizes Western philosophy, especially that of Hegel.
Rosenzweig also worked with his friend Martin Buber, another Jewish scholar, on a retranslation of the Old Testament, from Hebrew to German.
Rosenzweig also founded the Independent House of Jewish Learning, a place where Jews could re-discover and study their Jewish heritage. The Lehrhaus, as it was known in Germany, produced many prominent Jewish intellectuals.