The paradox within the title of this book refers to its principal theme, that of elucidating our innate capacity to transform/convert from an inauthentic everyday mode of being to an authentic one. This study provides an analysis of affect as a means of highlighting a number of key points of contact between the disciplines of philosophy and theology when addressing this topic. The author explores Martin Heidegger's intimate connections with Christianity, firstly, by examining the close ties he and his family had to the Catholic Church and, secondly, from within his fundamental ontology as developed in Being and Time. Finally, he demonstrates through literary and comparative analysis the affinity that exists between a philosophy of facticity and Christian theology in their descriptions of humankind without faith or Dasein's inauthentic existence.