One of the philosophical self-understanding texts of the 20th century that has so far received little attention is the fundamental debate that Jewish philosophers and theologians led after the National Socialists came to power. In newspapers, magazines and books, until the violent end of Jewish public life in Germany in 1938, there was still a passionate argument about contemporary and "true" Judaism for half a decade. Central interpretations beyond the much invoked "German-Jewish symbiosis" came mainly from the theological side. While the law-abiding Rabbi Alexander Altmann (1906–1987) clung to halachic Judaism as the central meaning for Jews, the young religious historian Hans-Joachim Schoeps (1909–1980) favored the content of Karl Barth's Christian dialectical theology. The common point of reference in these discussions was not infrequently Franz Rosenzweig (1886–1929), whose work had received a remarkable reception since 1933. In view of the existential threat, philosophers also participate in the controversy over the question "What is Judaism?" The essay mainly examines the polemic by Leo Strauss (1899–1973), whose book Philosophy and Law from 1935 had become a manifesto for contemporaries. His sharp criticism of the turning away from the sources of Judaism, as Maimonides (1138–1204) had canonized in his writings, resulted in a redefinition of the Enlightenment and tradition in Judaism. Among other things, the philosopher Julius Guttmann (1880–1950) and his student Fritz Bamberger (1902–1984) responded with a defense of liberal Judaism.