Introducing the Orthodox Church

Many people wonder what exactly the Orthodox Church is. In western countries like the United States and Great Britain, the Orthodox Church is very small in terms of actual members. People also frequently hear about The Greek Orthodox Church or The Russian Orthodox Church. Many wonder if there is a difference between the two churches. Many wonder if the Russian Orthodox and the Greek Orthodox are the same faith. In fact, the Greek and Russian Orthodox, as well as Orthodox Christians from many other nationalities all share the same faith as Orthodox Christians.
To better understand the Orthodox Church it requires a look back into history. Orthodox Christians consider themselves to be in a line going directly back to Christ and the apostles. The Orthodox can trace their history, in an unbroken chain of ordination directly back to Christ and the apostles. For this reason the Orthodox call their church apostolic.
After the death and resurrection of Jesus Christ the apostles went into much of the known world spreading the message of Christ's life , death and resurrection. Much of the missionary work was throughout the Mediterranean. As the message spread and the church grew, there were five major seats, or sees, where a bishop was located. These five sees were in Jerusalem, Antioch, Alexandria, Constantinople and Rome. When looking at a map of the Mediterranean it can be seen that Jerusalem, Antioch, Alexandria and Constantinople are all relatively close together in terms of geographical proximity, whereas Rome is further away. These sees were also in the East and possessed a different culture than that of Rome.
In the early days of the Church, there were many divergent beliefs, called heresies, which threatened the church. As a result, the Church convened meetings known as Ecumenical Councils to outline its faith and to overthrow heresies. Ultimately, up until the 8th century, the Church held seven ecumenical councils, none of which were attended by the bishop of Rome, in part due to geography and the political situation in the West at that point in time.
Eventually, over time, Eastern and Western Christianity became estranged from one another. The bishops of the East sided with one another over matters of doctrine and matters of ecclesiology and church government. The bishop of Rome gradually began to assert his position as the universal bishop of the Church, something to which the bishops of the East vehemently disagreed. This disagreement, along with other dogmatic issues, such as the wording of the Nicene-Constantinopolitan Creed, led to a split between East and West, usually historically dated to 1054. Those Christians who remained under Rome would come to be known as Roman Catholics, and those who operated more out of the collegial model in the East would be known as Orthodox or Eastern Orthodox Christians. The Eastern Church, when it went in to new territories or countries would take on the cultural character of that nation and, thus, the name of the nation as well. For this reason, in countries with high immigrant populations we see "Greek Orthodox" and "Russian Orthodox" reflecting the national background of the members of that particular church. However, in reality, all the members of these churches are members of the Orthodox Church, one Church, united by the same faith.