Phenomenology inspired and in turn was influenced by certain fundamental movements and developments in theology and religious studies in the twentieth century. Religious studies – discourse about religion as a cultural-sociological object, as distinct from theology as a discourse from within particular confessional denominations – developed through incorporating the phenomenological method. These influences were not simply one-way. The “new phenomenology” in France, starting from Levinas’ Totality and Infinity was inspired by such theological and religious thinkers as Rosenzweig, Buber, Weil, von Balthasar, Barth among others, so much so that this has been described as a “theological turn” in French phenomenology (Janicaud 2000). However, engagement with theology and religious phenomena has been a constant throughout phenomenology’s development and this is not so surprising: a philosophical discourse on phenomena cannot simply describe things appearing, but rather must account for the appearing of things. That appearing is not itself a thing that appears, but rather the unapparent in appearance. But precisely in attempting to account for that unapparent in appearance phenomenology comes very close to a mystical, religious or theological discourse.

Felix Ó Murchadha, "Philodophy of Religion and Theology," in Sebastian Luft and Søren Overgaard (eds.), Routledge Companion to Phenomenology, Abingdon: Routledge, 2012, p. 473