The subject of the research is the relationships between Turkey and the Fanar Greek Patriarchate in the context of international theories – realism and constructivism. The object of the study consists of the political-legal and ideological foundations of interaction between the parties, shaped by historical memory, normative discourses, and security considerations. The author examines in detail aspects such as Turkey's perception of the Patriarchate as a threat to national sovereignty, its claims to an "ecumenical" status and international recognition, as well as the role of the USA, the European Union, and Greece in supporting these claims. Special attention is given to how realism explains Turkey's defensive reflexes through the lens of security and balance of power, while constructivism reveals the processes of identity formation and legitimization of discourses. Collectively, the work demonstrates the multilayered nature of the problem, situated at the intersection of power struggles, normative conflicts, and identity contradictions. The research methodology is based on a comparative theoretical analysis of realism and constructivism, a discursive approach, and consideration of historical memory. Examples such as the Treaty of Lausanne, the closure of the Halki Theological School, and international reports are used to identify the interconnection between security, identity, and norms. The main conclusions of the conducted research reveal the relationship between security issues, identity, and international normative pressure in the relations between Turkey and the Fanar Patriarchate. A particular contribution of the author to the research is the application of both realist and constructivist perspectives, allowing for a demonstration of the limitations of one-dimensional explanations and the necessity of theoretical pluralism. The novelty of the study lies in considering the Patriarchate's issue not only as a religious or legal matter but as a multilayered phenomenon encompassing historical memory, the construction of national identity, and normative discourses. The work emphasizes that realism explains Turkey's desire to maintain the status quo, while constructivism reveals the mechanisms of legitimizing this status quo through norms and identity. Thus, the research contributes to a deeper understanding of the role of religious institutions in international relations.