Mahler’s innate spirituality, which we might read in modern terms as a tendency to be “spiritual but not religious” – has a long pedigree. Richard Wagner’s Religion und Kunst (1880) makes a distinction between inward faith, living and authentic, and outward religion, rigid and dogmatic. This contrast finds an important nexus in Austro-German lands in the latter half of the nineteenth century in three distinct areas that figured centrally in Mahler’s life: Jewish assimilation (including secularization and conversion); tendencies in Christianity, particularly Roman Catholicism; and the transference or sublimation of religious experience to the arts and particularly music (Kunstreligion). A born Jew, a converted Roman Catholic, and a lifelong Wagnerian, Mahler deemphasized the role of organized religion in his personal worldview, replacing it with the religious sensibility that is captured by the Wagnerian ideal of Kunstreligion.