The chapter argues that the aspects of Heidegger's thought which are most useful to feminist philosophy of religion are not the obviously spiritual terms, like Gelassenheit or "releasement" borrowed from Meister Eckhart, but instead the focus on co-existence and shared mood (Mitsein and Mitbefindlichkeit) to be found in Being and Time (1927). At the same time, these concepts represent a missed opportunity, as can be seen when Heidegger's arguments are juxtaposed with texts of fourteenth-century German mysticism and the milieu and practices from which these texts arose. The medieval texts supply a model for explaining why Heidegger's arguments about co-existence in the course of Being and Time unexpectedly come to privilege isolation and anxiety over being with other people. In particular, they make visible a culturally determined attachment to a model of masculine behaviour, that as well as being implicit in the arguments of Being and Time is explicit in the letters Heidegger wrote to Hannah Arendt in the mid-1920s.