What is the diffusion of Eastern Orthodoxy?

The diffusion of Eastern Orthodoxy primarily began with the Christianization of the Byzantine Empire in the 4th century, spreading through regions in Eastern Europe, the Balkans, and parts of the Middle East. It expanded further through missionary efforts, such as those by Saints Cyril and Methodius, who played a crucial role in converting the Slavic peoples. Over the centuries, Eastern Orthodoxy established a significant presence in countries like Russia, Greece, Serbia, and Bulgaria, often intertwining with national identities. Today, it remains a major branch of Christianity, with a strong cultural and spiritual influence in these regions.