After Christ’s resurrection and ascension, the Apostles appointed bishops to spread and preserve the faith within Christian communities they established throughout the region. During the early centuries of the Church, many bishops were martyred under persecution. Eventually, Christianity was accepted as the religion of the Roman Empire under Saint Constantine allowing for a unity of Christian communities to be recognized more broadly across the empire.
Among all of the communities established, some came to be recognized as highly influential metropolitan areas, including Rome, Antioch, Constantinople, Jerusalem, and Alexandria. These patriarchates all understood themselves to be the same Church.
Occasionally an idea contradicting of the faith received from the Apostles would take root in a community and stir up controversy. Ecumenical Councils consisting of representation from all of the Church were called to resolve the dispute. One of the familiar outcomes of those first councils to address heresies was the Nicene-Constantinopolitan creed.
Christianity continued to spread throughout the east, including Russia in the 10th century.
Increasing tensions between the Roman bishop and the Eastern bishops eventually led to the “Great Schism” in the 11th century. Over the next centuries, theological and political divisions between Rome and the Eastern Patriarchates became more solidified, eventually resulting in a universal recognition of the loss of communion.
The Reformation of the 16th century resulted in further divisions within the Roman church as new national churches were established throughout Europe over the following centuries. Many of the first Europeans that came to North America were from the Roman Catholic Church and other reformation churches.
Orthodoxy was first brought to North America by Russian missionaries sent to Alaska. Other immigrants arriving in other areas of the US set up churches under supervision of bishops in their native countries. Orthodoxy in America is still administered among multiple jurisdictions, but they share participation in the Assembly of Canonical Orthodox Bishops of the United States of America which is working towards a unified administration of Orthodoxy in the US.