Editing History of Christianity (section)

=== Heresies, schisms and councils ===
[[File:First Nicea Council Icon from Protatos Church, 1770.jpg|thumb|[[First Council of Nicaea]] icon from Protatos Church, 1770|alt=icon of first Nicene council]]
Regional variants of Christianity produced diverse and sometimes competing theologies.{{sfn|Casiday|Norris|2007|p=2}}{{sfn|Lyman|2007|pp=308-309}} Ancient Christian authors identified any practice or doctrine which differed from apostolic tradition as [[heresy]].{{sfn|Praet|1992–1993|pp=68, 108}}{{sfn|Iricinschi|Zellentin|2008|p=4}}{{sfn|McGinn|2017|pp=838–841}} The number of laws directed at heresy indicate it was a much higher priority than paganism for Christians of this period.{{sfn|Brown|1998|pp=634, 640, 651}}{{sfn|Salzman|1993|p=375}}

For decades, [[Arianism]] embroiled the entire church, [[Catholic laity|laity]] (non-clergy) and clergy alike, in arguing whether Jesus' divinity was equal to the Father's.{{sfn|Goodman|2007|pp=30–32}}{{sfn|Berndt|Steinacher|2014|p=9}}{{sfn|Rankin|2017|p=908}} The [[First Council of Nicaea]] in 325 attempted to resolve the controversy with the [[Nicene Creed]], but some refused to accept it.{{sfn|Berndt|Steinacher|2014|pp=2, 4, 7}}{{sfn|Cameron|2006b|p=545|loc="In one of the most momentous precedents of his reign, during Constantine's twentieth-anniversary celebrations in 325, some 250 bishops assembled at Nicaea..."}} The development of heresy demonstrated the importance of boundaries, which became a force for social stability through cultural assimilation.{{sfn|Lyman|2007|pp=308-309}} Along the Eastern Mediterranean, where Christian factions struggled without resolution, Christian communities were weakened, affecting their long-term survival.{{sfn|Casiday|Norris|2007|p=4}}

Christian scriptures were formalized as the [[New Testament]] and distinguished from the Old Testament by the fourth century.{{sfn|Westcott|2005|pp=12–13}}{{sfn|Bruce|1988|p=215}} Despite agreement on these texts, differences between East and West were becoming evident.{{sfn|Brown|2010|loc=Intro. and ch. 1}}{{sfn|Brown|1976|p=2}}{{sfn|Hamilton|2003|pp=68-71}} The West was solidly Nicean while the East was largely Arian.{{sfn|Thompson|2016|p=27}} The West condemned Roman culture as sinful and resisted state control, whereas the East harmonized with Greek culture and aimed for unanimity between church and state.{{sfn|Drake|2007|pp=416; 418}}{{sfn|Brown|1976|pp=7–8}}{{sfn|Mathisen|2002|p=261}} The marriage of clerics was accepted in the East but forbidden in the West.{{sfn|Shaw|2017|p=365}}{{sfn|Stewart|2017|pp=308, 324}} The East advocated [[pentarchy|sharing the government of the church]] between five church leaders, arguing that the [[Patriarch|Patriarchs]] of [[Ecumenical Patriarch of Constantinople|Constantinople]], [[Patriarch of Alexandria|Alexandria]], [[Patriarch of Antioch|Antioch]], and [[Greek Orthodox Patriarch of Jerusalem|Jerusalem]] were equal to the Pope. Rome asserted that successors to Peter had [[papal primacy|superiority]].{{sfn|Nelson|2008|p=301}}{{sfn|Hamilton|2003|p=63}}

Controversies over how Jesus' human and divine natures coexisted peaked when [[Nestorius]] declared Mary as the mother of Jesus' humanity, not his divinity, thereby giving Jesus two distinct natures.{{sfn|Ware|1993|pp=31-32}} This led to a series of [[ecumenical council]]s: the [[Council of Ephesus]] was the church's third council, and it condemned Nestorius. Held in 431, the church in the Persian Empire refused to recognize its authority. This led to the first separation between East and West. Two groups, one mostly Persian and the other Syrian, separated from Catholicism; Persians became the [[Church of the East]] (also known as the Assyrian, Nestorian, or Persian Church), while the majority of Christians in Syria and Mesopotamia became the [[Syrian Orthodox Church]] (Jacobite).{{sfn|Hamilton|2003|pp=178, 180}}{{refn|group=note|The second group includes the ([[Syriac Orthodox Church|Syrian Church of Antioch]]), [[Malankara Orthodox Syrian Church|Syrian Church in India]], [[Coptic Orthodox Church|Coptic Church in Egypt]], [[Armenian Apostolic Church|Armenian Church]], and [[Ethiopian Orthodox Tewahedo Church|Ethiopian Church]].{{sfn|Ware|1993|p=11}}{{sfn|Hamilton|2003|pp=177-178}}}} This cut off the flourishing school of Syrian Semitic Christian theologians and writers from the rest of Christendom.{{sfn|Ware|1993|p=12}} The Church of the East lay almost entirely outside the Byzantine Empire.{{sfn|Ware|1993|p=35}} It became the principal Church in Asia in the Middle Ages.{{sfn|Hamilton|2003|pp=xii, 177}} 

In 451, the fourth council was the influential [[Council of Chalcedon]].{{sfn|Sabo||2018|p=vii}}{{refn|group=note|The [[Second Council of Constantinople|Fifth]] was in 583, and the [[Third Council of Constantinople|Sixth]] in 680{{Endash}}681.{{sfn|Sabo||2018|p=vii}} The seventh council of the church in 787, the [[Second Council of Nicaea]], was the last one recognized as a general council by the Byzantine Church.{{sfn|Hamilton|2003|p=67}}}} While most of Christianity accepted the [[Chalcedonian Definition]], which emphasizes that the Son is "one person in two natures," there were those who found that description too close to the duality of Nestorianism, so after 484, they separated into [[History of Oriental Orthodoxy|Oriental Orthodoxy]] that sees only [[Miaphysitism|"One Nature of God the Incarnate Logos"]].{{sfn|Chaillot|2016|p=273}}{{sfn|Löhr|2007|loc=abstract}}{{sfn|Cross|2001|p=363}}