In the West after the fall of the Roman Empire, the church assumed the unifying social function that no other individual or institution was able to fulfill. Eventually the popes assumed civil authority in Christendom (according to the false Donation of Constantine, the first Christian emperor actually bestowed authority over the Western Empire on the pope). In the East the empire persisted until 1453 and in Russia until 1917. Thus, the church had to fulfill its social functions in the political framework of the Christian empire.

This historical contrast coincides with a theological polarization: the Eastern Fathers conceived the God-human relationship in terms of personal experience and communion culminating in deification. Western theology, meanwhile, understood man as autonomous in the secular sphere, although controlled by the authority of the church, which was conceived as vicariously representing God.

The Byzantine and Eastern form of church-state relations has often been labelled as caesaropapism, and the hierarchy of the church was, most of the time, deprived of the legal possibility of opposing imperial power. But this label is inaccurate in two respects: first, it presupposes that the emperor possessed a recognizable power to define the content of the faith, comparable to that of the papacy; and, second, it underestimates the power of the church (as a corporate, transfiguring, and deifying power) that is effective without legal guarantees or statutes. The Byzantine ideal of church-state relations was a “symphony” between the civil and the ecclesiastical functions of Christian society. The abuses of imperial power were frequent, but innumerable examples of popular resistance to those imperial decrees that were considered as detrimental to the faith can be cited. Neither the strong emperors of the 7th century, trying to impose monophysitism, nor the weakened Palaeologans (13th–15th century), attempting reunion with Rome, were able to overcome the corporate opposition of Orthodox clergy and laity.

The Byzantine conception of church-state relations was not, however, without major weaknesses. It often led to the identification of the interests of the church with those of the empire. Conceived when both the church and the empire were supranational and, in principle, universal, it gradually evolved into a system that gave a sacred sanction to national states. Modern ecclesiastical nationalism, which inhibits relations between Orthodox churches, is the outcome of the medieval alliance between the empire and the church.

Only after the Turkish occupation of the Balkans was civil authority directly assumed by the Orthodox church hierarchy in the Middle East. It was granted to it by the new Muslim overlords, who chose to administer their Christian subjects as a separate community, or millet, ruled by its own religious leaders. The patriarch of Constantinople was thus appointed by the sultan as head (millet-bachi) of the entire Christian population of the Ottoman Empire. Understood by some, especially the Greeks, as the heir of Byzantine emperors and by others, especially the Balkan Slavs and Romanians, as an agent of the hated Turks, the patriarch exercised these powers until the secularization of the Turkish republic by Kemal Atatürk, the founder and first president of the republic, in 1921. By that time, however, the patriarch had lost most of his jurisdictional powers because of the establishment of autocephalous churches in Greece, Serbia, Bulgaria, and Romania. The millet system, however, survived in other areas of the Middle East. In Cyprus, for example, the church assumed a leading role in national liberation, and its prestige encouraged the election of Archbishop Makarios III as the first president of the young republic.

The millet system and the active political responsibilities that it implied for the church, it should be noted, originated in the Ottoman period only and is not in the spiritual tradition of the Christian East as such. The Russian church is the most recent example of religious survival without practical social or political involvement.

The Orthodox attitude toward social responsibility in the world constitutes a distinct contribution to the contemporary ecumenical movement. But it will be meaningful only if it is understood in its proper framework—i.e., as an understanding of the Christian faith as a personal spiritual experience of God, which is self-sufficient knowledge of God and which, as such, can lead to an authentically Christian witness in the secularized world. The form of that witness has varied greatly in history, and Orthodox tradition has placed among the church’s saints both hermits and politicians, Hesychast monks as well as emperors. According to the modern Orthodox theologian Sergey Nikolayevich Bulgakov, the Orthodox church accepts “a relativism of means and methods,” provided there remains “an absolute and unique goal,” which is the kingdom of God still to come but also already present in the mystery of the church.