This volume presents the theory of culture of the Russian-born German Jewish social philosopher David Koigen (1879–1933). Heir to Hermann Cohen’s neo-Kantian interpretation of Judaism as a religion of reason, he draws upon philosophical anthropology and the sociology of religion to go beyond Kantian formalism. The resulting primacy given to religious consciousness brought him close to Martin Buber, with whom he shared an interest in East European Hasidism as a source of religious renewal. Author of Ideen zur Philosophie der Kultur (1910) and Der moralische Gott (1922), among other works, Koigen enters a much wider debate on the relation between religion, culture and conceptions of the nation, developing a non-essentialist approach to religion and ethnicity. Enjoining the concept of ethos as the arbiter of ethnos and ethics he formulates a theory of culture on the basis of Jewish monotheism that would pose a challenge to Liberal Judaism and Liberal Protestantism alike. Among his interlocutors were Max Scheler, Georg Simmel, Ernst Troeltsch, and Max Weber. His elucidation of the complex interplay between Judaism’s concept of covenant and its attendant ethos offers a novel approach to the construction of a modern Jewish identity. The theoretical value of the notion of ethos for the sociology of religion is most succinctly expressed in a lecture on the ethos in Judaism which is presented and annotated for a first time in this volume.