Greek Orthodox Church

• The broader meaning refers to "the entire body of Orthodox (Chalcedonian) Christianity, sometimes also called 'Eastern Orthodox', 'Greek Catholic', or generally 'the Greek Church'".
• A second, narrower meaning refers to "any of several independent churches within the worldwide communion of Eastern Orthodox Christianity that retain the use of the Greek language in formal ecclesiastical settings". In this sense, the Greek Orthodox churches are the Ecumenical Patriarchate of Constantinople and its dependencies, the patriarchates of Alexandria, Antioch and Jerusalem, the Church of Greece and the Church of Cyprus.
• The third meaning refers to the Church of Greece, an Eastern Orthodox Church operating within the modern borders of Greece.

Etymology

Historically, the term "Greek Orthodox" has been used to describe all Eastern Orthodox churches, since the term "Greek" can refer to the heritage of the Byzantine Empire. During the first eight centuries of Christian history, most major intellectual, cultural, and social developments in the Christian Church took place in the Byzantine Empire or its sphere of influence, where the Greek language was widely spoken and used for most theological writings. The empire's capital, Constantinople, was an early important center of Christianity, and its liturgical practices, traditions, and doctrines were gradually adopted throughout Eastern Orthodoxy, still providing the basic patterns of contemporary Orthodoxy. Thus, Eastern Orthodox came to be called "Greek" Orthodox in the same way that Western Christians came to be called "Roman" Catholic. However, the appellation "Greek" was abandoned by the Slavic and other Eastern Orthodox churches as part of their peoples' national awakenings, beginning as early as the 10th century A.D. Thus, by the early 21st century, generally only those churches most closely tied to Greek or Byzantine culture and ethnicity were called "Greek Orthodox" in common parlance.

Greek Orthodoxy has also been defined as a religious tradition rooted in preserving the Greek identity. In 2022, U.S. government estimated that 81–90% of the population of Greece identified as Greek Orthodox.