The term is generally used in Western Christianity to describe all Christian traditions that did not develop in Western Europe. As such, the term does not describe any single communion or common religious tradition, and in fact some "Eastern" Churches have more in common historically and theologically with "Western" Christianity than with one another. The various "Eastern" Churches do not normally refer to themselves as "Eastern," with one exception (the Church of the East).
The terms "Eastern" and "Western" in this regard originated with divisions in the Church mirroring the cultural divide between the Hellenistic east and Latinate west and the political divide between the weak Western and strong Eastern Roman empires. Because the most powerful Church in the East was what has become known as the Eastern Orthodox church, the term "Orthodox" is often used in a similarly loose fashion as "Eastern", although strictly speaking most Churches consider themselves part of an Orthodox and Catholiccommunion.
Eastern Christians do not have shared religious traditions but many of these groups have shared cultural traditions. Christianity divided itself in the East during its early centuries both within and outside of the Roman Empire in disputes about Christology and fundamental theology, as well as national divisions (Roman, Persian, etc.). It would be many centuries later that Western Christianity fully split from these traditions as its own communion. Today there are four main branches or families of Eastern Christianity, each of which has distinct theology and dogma.
The First Council of Nicaea, held in Nicaea in Bithynia (present-day Iznik in Turkey), convoked by the Roman EmperorConstantine I in 325, was the first Ecumenical council of the early Christian Church, and most significantly resulted in the first uniform Christian doctrine, called the Nicene Creed. With the creation of the creed, a precedent was established for subsequent 'general (ecumenical) councils of Bishops' (Synods) to create statements of belief and canons of doctrinal orthodoxy— the intent being to define unity of beliefs for the whole of Christendom. The Council of Nicaea was historically significant because it was the first effort to attain consensus in the church through an assembly representing all of Christendom. "It was the first occasion for the development of technical Christology." Further, "Constantine in convoking and presiding over the council signaled a measure of imperial control over the church." Further, a precedent was set for subsequent general councils to create creeds and canons. The long-term effects of the Council of Nicaea were significant. For the first time, representatives of many of the bishops of the Church convened to agree on a doctrinal statement. Also for the first time, the Emperor played a role, by calling together the bishops under his authority, and using the power of the state to give the Council's orders effect.
The nave of the Hagia Sophia Church, the second oldest church in the Bulgarian capital Sofia. The present basilica dates to the 6th century and is believed to be the fifth structure to be constructed on the site. The city took its name from the church in the 14th century. It is now one of the most valuable pieces of Early Christian architecture in southeastern Europe.
Gregory made a significant impact on the shape of Trinitariantheology among both Greek- and Latin-speaking theologians, and he is remembered as the "Trinitarian Theologian". Much of his theological work continues to influence modern theologians, especially in regard to the relationship among the three Persons of the Trinity. Along with two brothers, Basil the Great and Gregory of Nyssa, he is known as one of the Cappadocian Fathers.