Theosophy would not have emerged as a widespread global phenomenon in the nineteenth century had its ascendancy not also coincided with the growing appeal of scientific monism as one of the most potent challenges to Christianity's body-soul dualism. Theosophy, like other alternative religious movements that gathered momentum in the nineteenth century as the crisis of faith grew, constituted a heterodox response to the monochromatic character of mainstream religion, refusing both the authoritarian certainties of dogmatic theology and the materialism of secular reason. With roots in an eclectic blend of Renaissance Neoplatonism, Kabbalism, and Christian and Jewish mysticism, Theosophy nonetheless maintained an intense engagement with nineteenth-century science. Its self-positioning between science and religion grew out of Theosophy's interventions in the debates over mind and matter, which pitted the monistic view that mind is matter against Christianity's body-soul dualism.