Orthodox Christians consider themselves to be part of one church in the sense that they share the same faith and sacraments, as well as the Byzantine liturgical, canonical, and spiritual tradition. All Orthodox recognize the first seven ecumenical councils as normative for doctrine and church life. A number of later councils are also considered to express the same original faith. Although referred to most commonly as the Orthodox Church, this communion is also frequently called the Eastern Orthodox Church to distinguish it from the Oriental Orthodox churches described in the previous section.
At the level of church government, Orthodoxy is a communion of churches, all of which recognize the Patriarch of Constantinople as primus inter pares, or “first among equals.” Although he does not have authority to intervene in the affairs of local churches outside his own Patriarchate, he is considered first in honor and the symbolic center of all the Orthodox churches. Thus the Patriarchate of Constantinople (also known as the Ecumenical Patriarchate) enjoys a certain priority among the various Orthodox churches. It sees this status as a service that provides a mechanism for promoting conciliarity and mutual responsibility. This role includes convoking the churches and coordinating their activity, and at times intervening in situations in an effort to find solutions to specific problems.
The schism between what are now known as the Orthodox and Catholic churches was the result of a centuries-long process of estrangement. Such events as the excommunications in 1054 between the Patriarch of Constantinople and the papal legate were only high points in this process. Moreover, each Orthodox church has its own history concerning the rift with Rome. There was never, for example, a formal separation between Rome and the Patriarchate of Antioch, although Antioch came to share the common Byzantine perception of the schism. Today it is widely agreed that there were significant non-theological factors at play in this gradual alienation between East and West. These included the interruption of regular communication that resulted from political developments and the loss of the ability to understand the Greek or Latin of the other church. But doctrinal issues were also involved, especially regarding the nature of the Church. The most important of these concerned the eternal procession of the Holy Spirit (related to the addition of the filioque to the Creed by the western church), and the meaning of the role of the bishop of Rome as first bishop in the Church.
Two major attempts to reestablish communion between Catholics and Orthodox took place at the Second Council of Lyons in 1274 and the Council of Florence-Ferrara in 1438-1439. Although formal reunions were proclaimed in both cases, they were ultimately rejected by the general Orthodox population. Many centuries of mutual isolation have been ended only in the contemporary period. An official international dialogue between the two churches has been in progress since 1980.