Chalcedonian in the context of "Greek Orthodox patriarch of Antioch"

The Chalcedonian schism, also known as the Monophysite schism, is the break of communion between the Oriental Orthodox Churches and the Great Church (which later became the Eastern Orthodox Church and Catholic Church) in the aftermath of the Council of Chalcedon. Although the bishops at Chalcedon greatly respected Cyril of Alexandria and used his writings as a benchmark for orthodoxy, opponents of the council believed that the Chalcedonian Definition, which states that Christ is "acknowledged in Two Natures", was too close to Nestorianism and contradicts Cyril's formula "one nature of God the Word incarnate". The Council had also deposed the Pope of Alexandria, Dioscorus, but his supporters continued to consider him their rightful Pope, refusing to recognise the council-appointed Proterius.

The anti-Chalcedonian strongholds were in Egypt, Palestine and later Syria. Over the next century, their communities gradually separated from the official church of the Byzantine Empire, eventually becoming the Oriental Orthodox Churches. The imperial government made many attempts to mend the schism, generally by trying to compromise between the two positions, but these attempts only created further heresies and schisms. The Arab conquests of the Levant and of Egypt in the 7th century fossilised the schism, but ecumenical dialogue between Chalcedonian and non-Chalcedonian Christians has been renewed since the 20th century.

The theme of Iberia (Greek: θέμα Ἰβηρίας) was an administrative and military unit (theme) within the Byzantine Empire carved by the Byzantine Emperors out of several Georgian lands in the 11th century. It was formed as a result of Emperor Basil II’s annexation of a portion of the Bagrationi dynasty domains (1000–1021) and later aggrandized at the expense of several Armenian kingdoms acquired by the Byzantines in a piecemeal fashion in the course of the 11th century. The population of the theme—at its largest extent—was multiethnic with a possible Georgian majority, including a sizable Armenian community of Chalcedonic rite to which Byzantines sometimes expanded, as a denominational name, the ethnonym "Iberian", a Graeco-Roman designation of Georgians. The theme ceased to exist in 1074 as a result of the Seljuk invasions.

The Chalcedonian Definition (also called the Chalcedonian Creed or the Definition of Chalcedon) is the declaration of the dyophysitism of Christ's nature, adopted at the Council of Chalcedon in AD 451. Chalcedon was an early centre of Christianity located in Asia Minor. The council was the fourth of the ecumenical councils that are accepted by Chalcedonian churches which include the Catholic and Orthodox churches.

It was the first council not to be recognised by any Oriental Orthodox church; for this reason these churches may be classified as Non-Chalcedonian.

The Three-Chapter Controversy, a phase in the Chalcedonian controversy, was an attempt to reconcile the non-Chalcedonians of Syria and Egypt with Chalcedonian Christianity, following the failure of the Henotikon. The Three Chapters (τρία κεφάλαια, tría kephálaia) that Emperor Justinian I anathematized were:

1. The person and writings of Theodore of Mopsuestia
2. Certain writings of Theodoret of Cyrus
3. The letter of Ibas of Edessa to Maris

The Byzantine Empire was ruled by emperors of the dynasty of Heraclius between 610 and 711 AD. The Heraclians presided over a period of cataclysmic events that were a watershed in the history of the Empire and the world. Heraclius, the founder of his dynasty, was of Armenian and Cappadocian (Greek) origin. At the beginning of the dynasty, the Empire's culture was still essentially Ancient Roman, dominating the Mediterranean and harbouring a prosperous late antique urban civilization. This world was shattered by successive invasions, which resulted in extensive territorial losses, financial collapse and plagues that depopulated the cities, while religious controversies and rebellions further weakened the Empire.

By the dynasty's end, the Empire had been transformed into a different state structure: now known in historiography as medieval Byzantine rather than (Ancient) Roman, a chiefly agrarian, military-dominated society that was engaged in a lengthy struggle with the Muslim Rashidun Caliphate and successor Umayyad Caliphate. However, the Empire during this period became also far more homogeneous, being reduced to its mostly Greek-speaking and firmly Chalcedonian core territories, which enabled it to weather these storms and enter a period of stability under the successor Isaurian dynasty.