The Orthodox Church has existed since the day of Pentecost, and has not changed since.
In its infancy, or the Age of the Apostles,
The Orthodox Church developed as the Apostles, who moved from place to place setting up "house" churches wherever they went. Once the founding Apostles left a newly formed church, a hierarchy of administrators, bishops, priests, and deacons formed to take stationary positions in the new church. This leadership system of bishops, priests and deacons still exists today.
sourceIn the Fourth Century
Constantine, recognizing Christianity as the new religion of the state, moves the capitol, “the center of Roman government” from Rome to Constantinople. This began the great schism in the Orthodox Church which split the Church into two distinct pieces:
The system was later broken down due to constant attacks by rival tribes which drove a wedge between the two halves of the Roman empire making it too difficult for travel into or out of the area. Meanwhile, in the east, the Roman Empire barely survived these tribal attacks, eventually becoming the Byzantine Empire.
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