Eastern Orthodox Church
The Orthodox Church, officially called the Orthodox Catholic Church and commonly referred to as the Eastern Orthodox Church, is body of modern churches, including among others the Greek and Russian Orthodox, that is derived from the church of the Byzantine Empire, adheres to the Byzantine Rite, and acknowledges the honorary primacy of the patriarch of Constantinople.
Orthodoxy is a form of Christianity that developed first in the Eastern Roman Empire (which spanned present-day Greece, Turkey, and the Middle East) and later in the Slavic lands of eastern Europe. The Orthodox Church sees itself as the authentic continuation of the first Christian communities established by the apostles of Jesus in the cities of the ancient Mediterranean world and spread by missionary activity throughout eastern Europe. Today most Orthodox Christians live in Russia, eastern Europe, or on the Balkan Peninsula, but there are also large Orthodox communities in North and South America as well as Australia, and smaller numbers in western Europe, Africa, and Asia. By the year 2000 the Orthodox Church had about 210 million adherents throughout the world. Of these, about 15 million are Greek-speaking; the rest speak Slavic or other European languages, or Arabic. Alternative designations, such as Catholic Apostolic and Orthodox, Greek Orthodox, and Eastern Orthodox, are also used in reference to the Orthodox Church.
Christianity began in the Roman Empire in the first century. It flourished especially in the eastern territories of the empire. By the end of the 4th century, it had become the official religion of the empire. By late in the 5th century the Roman Empire in the Latin-speaking West had fallen into political ruin, but it continued in the Greek-speaking eastern Mediterranean region for another thousand years, with a succession of emperors, a powerful army, and a lively Greek Christian culture. The later Roman Empire is commonly known as the Byzantine Empire, with its capital at the “new Rome” of Constantinople (now İstanbul, Turkey). After the 5th century the religious cultures of Greek-speaking and Latin-speaking Christians began increasingly to diverge, and cultural alienation set in. In 1054 the leaders of the Roman Catholic and Eastern Orthodox Christians formally condemned one another for having introduced innovations into Christianity, and the alienation was given formal status as a schism (division). Since that time Christianity in eastern and western Europe has had decidedly different histories.