The newly-converted Emperor Constantine had hoped Christianity would be the uniting force of his empire. He was thus distressed to hear of the dispute over Arianism, which held that Christ was greater than man but inferior to God. In 325, Constantine called the Council of Nicea with full confidence that the bishops could work out their differences.

The gathering must have been a moving sight to behold. After centuries of persecution, Christian bishops from across the Empire journeyed to Nicea under state protection to discuss theological problems with the help of the Emperor. Official persecution had been so recent that many of the bishops still bore its scars; Constantine himself is said to have kissed the eyeless cheek of one attendee.

The Council of Nicea condemned the teachings of Arius and adopted a creed outlining correct belief about the Son's relationship to the Father. The council was the first to include bishops from several different regions, and is thus considered the first "ecumenical council" of the church. Although many other local synods were held, seven important councils were attended by representatives of churches throughout the empire, and were therefore "ecumenical." All three main branches of Christianity - Roman Catholic, Eastern Orthodox, and Protestant - consider the decisions of these seven councils to be authoritative. Roman Catholics recognize several more.

Nicaea İznik (which derives from the former Greek name Νίκαια, Nicaea) is a city in Turkey which is known primarily as the site of the First and Second Councils of Nicaea, the first and seventh Ecumenical councils in the early history of the Christian church, the Nicene Creed, and as the capital city of the Empire of Nicaea (i.e. interim capital city of the Byzantine Empire between 1204 and 1261, following the Fourth Crusade in 1204, until the recapture of Constantinople by the Byzantines in 1261).

Arian

Date:14th century

 : of or relating to Arius or his doctrines especially that the Son is not of the same substance as the Father but was created as an agent for creating the world

Catholic-Orthodox joint declaration of 1965 (from the Vatican site)

Catholic-Orthodox joint declaration of 1965

The Eastern Orthodox Church (i.e. Greek Orthodox, Russian Orthodox, etc.) is the modern name commonly applied to the ancient, theologically unified, multinational Christian communion that views itself as:

·               The historical, unbroken continuation of the original Christian community established by Jesus Christ, the Twelve Apostles, and St. Paul, having preserved the apostolic traditions handed down to them, and having maintained unbroken the link between its clergy and the Apostles by means of Apostolic Succession.

·               The ecclesial communion which has never fallen into error nor deviated from the beliefs and traditions of the original Christian body, but rather has gone to great lengths to preserve them for future generations. All theological concepts, all explanations and expansions are compared to and validated by the original core beliefs; no deviation is allowed.

·               The Christian body which most closely adheres to the canons of the first seven ecumenical councils held between the 4th and the 8th centuries.

Note: Members of the Eastern Orthodox Church do not usually refer to themselves as "Eastern" Orthodox but rather with a prefix denoting their nation of origin. Thus, within this article, the terms Greek, Russian, Romanian, Serbian, Antiochian, or any national Orthodox; The Church, The Orthodox Church, The Byzantine Church, etc., all refer to a single unified entity, what is today commonly called the Eastern Orthodox Church.

The Roman Catholic Church or Catholic Church (see terminology below) is the Christian church that is in full communion with the Bishop of Rome, currently Pope Benedict XVI. It traces its origins to the original Christian community founded by Jesus and spread by the Twelve Apostles, in particular Saint Peter.^[1][2]

The Catholic Church is the largest Christian church, representing about half of all Christians, and is the largest organized body of any world religion.^[3][4] According to the Statistical Yearbook of the Church, the Catholic Church's worldwide recorded membership at the end of 2005 was 1,114,966,000, approximately one-sixth of the world's population.^[5][6][7]

The worldwide Catholic Church is made up of one Western or Latin and 22 Eastern Catholic autonomous particular churches, all of which look to the Bishop of Rome, alone or along with the College of Bishops, as their highest authority on earth for matters of faith, morals and church governance.^[8] It is divided into jurisdictional areas, usually on a territorial basis. The standard territorial unit, each of which is headed by a bishop, is called a diocese in the Latin church and an eparchy in the Eastern churches. At the end of 2006, the total number of all these jurisdictional areas (or "Sees") was 2,782.^[9]

Eastern Orthodox

Date:1909

 : of or consisting of the Eastern churches that form a loose federation according primacy of honor to the patriarch of Constantinople and adhering to the decisions of the first seven ecumenical councils and to the Byzantine rite

Byzantine

Date:1651

1 : of, relating to, or characteristic of the ancient city of Byzantium

2 : of, relating to, or having the characteristics of a style of architecture developed in the Byzantine Empire especially in the fifth and sixth centuries featuring the dome carried on pendentives over a square and incrustation with marble veneering and with colored mosaics on grounds of gold

3 : of or relating to the churches using a traditional Greek rite and subject to Eastern canon law

4 often not capitalized    a : of, relating to, or characterized by a devious and usually surreptitious manner of operation  *a Byzantine power struggle*  b : intricately involved  : LABYRINTHINE  *rules of Byzantine

The Byzantine Empire or Byzantium is the term conventionally used since the 19th century to describe the Greek-speaking Roman Empire of the Middle Ages, centered on its capital of Constantinople. The Empire is also known as the Eastern Roman Empire, although this name is more commonly used when referring to the time before the fall of the Western Roman Empire. During much of its history it was known to many of its Western contemporaries as the Empire of the Greeks because of the dominance of Greek language, culture and population.^[1] To its inhabitants, the Empire was simply the Roman Empire (Greek: Βασιλεία Ῥωμαίων) and its emperors continued the unbroken succession of Roman emperors. In the Islamic world it was known primarily as روم‎ (Rûm, land of the "Romans").

There is no consensus on exactly when the Byzantine period of Roman history began. Many consider Emperor Constantine I (reigned AD 306–337) to be the first "Byzantine Emperor". It was he who moved the imperial capital in 330 from Rome to Byzantium, refounded as Constantinople, or Nova Roma ("New Rome").

Ecumenical

Etymology:Late Latin oecumenicus, from Late Greek oikoumenikos, from Greek oikoumen* the inhabited world, from feminine of oikoumenos, present passive participle of oikein to inhabit, from oikos house — more at  VICINITY

Date:circa 1587

1 : worldwide or general in extent, influence, or application

2 a : of, relating to, or representing the whole of a body of churches  b : promoting or tending toward worldwide Christian unity or cooperation

Creed

Etymology:Middle English crede, from Old English cr*da, from Latin credo (first word of the Apostles' and Nicene Creeds), from credere to believe, trust, entrust; akin to Old Irish cretid he believes, Sanskrit Krad-dadh*ti

Date: before 12th century

1 : a brief authoritative formula of religious belief

2 : a set of fundamental beliefs;  also   : a guiding principle

Nicene

Etymology:Middle English, from Late Latin nicaenus, from Latin Nicaea Nicaea, from Greek Nikaia

Date:14th century

1 : of or relating to Nicaea or the Nicaeans

2 : of or relating to the ecumenical church council held in Nicaea in A.D. 325 or to the

Nicene Creed

Date:circa 1569

 : a Christian creed expanded from a creed issued by the first Nicene Council, beginning *I believe in one God,* and used in liturgical worship Nicene Creed

Nestorius (c. 386–c. 451) was a pupil of Theodore of Mopsuestia in Antioch in Syria (modern Turkey) and later became Archbishop of Constantinople. He taught that the human and divine aspects of Christ were distinct natures, not unified. He preached against the use of the title Mother of God (Theotokos) for the Virgin Mary and would only call her Mother of Christ (Christotokos). He also argued that God could not suffer on the cross, as he is omnipotent. Therefore, the human part of Christ died on the cross, but not the divine.

His opponents accused him of dividing Christ into two persons: they claimed that proposing that God the Word did not suffer and die on the cross, while Jesus the man did, or that God the Word was omniscient, while Jesus the man had limited knowledge, implied two separate persons with separate experiences.

Nestorius responded that he believed that Christ was indeed one person (Greek: prosopon). Opposed by Cyril of Alexandria, Nestorius was condemned at the Council of Ephesus in 431.

The Council held that Christ is one person, and that the Virgin Mary is the mother of God. The condemning pronouncement of the Council resulted in the Nestorian schism and the separation of the Assyrian Church of the East from the Byzantine Church.[1] However, even Ephesus could not settle the issue, and the Byzantine Church was soon split again over the question of whether Christ had one or two natures, leading to the Chalcedonian schism.