The central aim of this dissertation is to offer a focused study on Christos Yannaras’ unexplored response to Martin Heidegger’s onto-theological critique of metaphysics, with the further intention of advancing Yannaras’ proposal as a possible way forward from the metaphysical impasse of Western nihilism in the emerging field of Continental philosophy of religion. Accordingly, this essay sets out to address the following questions: how and in what way can Yannaras’ response overcome the metaphysical impasse of Western nihilism as illuminated by Martin Heidegger? Further still, this inquiry gives rise to the following question: how in and what way does Yannaras’ response contribute to contemporary post-Heideggerian discourse? In response to the first question, this essay will argue that Yannaras’ response to Heidegger’s critique is able to overcome the metaphysical impasse of Western nihilism by A) arguing that the historical unfolding of nihilism is an event that must be restricted to the Latin (Western European) philosophical tradition alone, and thus neither accounts for nor applies to the non-Western, Hellenistic tradition of the Christian East, which he summarizes as the philosophical tradition of the Greek Church Fathers. Second, and for this reason, Yannaras is able to B) present the tradition of the Greek Church Fathers as capable of successfully overcoming the nihilistic implications of Heidegger’s fundamental ontology insofar as he believes it to offer a non-essentialist, testimonial metaphysics of ecclesial existence which is not derived from the onto-theological structure of value-laden metaphysics, but is capable of being known and validated through praxis, participation, and intersubjective experience. In response to the second question, I will then argue that C) Yannaras’ ontological understanding of ecclesial existence offers a key methodological hermeneutic which would allow for richer discourse amongst Christian thinkers within the post-Heideggerian field of Continental philosophy of religion insofar as it would not restrict phenomenological discourse within Christianity to theology or religion, but would open the possibility for Christian experience to be discussed ontologically within the discipline of philosophy proper.