Great Church in the context of "Old Catholic Church"

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.

Christianity in the ante-Nicene period was the period in Christian history following the Apostolic Age (1st century AD) up to the First Council of Nicaea (325 AD). Although the use of the term Christian (Koine Greek: Χριστιανός) is attested in the Acts of the Apostles (80–90 AD), the earliest recorded use of the term Christianity (Koine Greek: Χριστιανισμός) is attested by the ante-Nicene Father and theologian Ignatius of Antioch (c. 107 AD).

While the Jewish–Christian community was centered in Jerusalem in the 1st century AD, Gentile Christianity spread widely in the 2nd century AD. One stream of Gentile Christianity (so-called "proto-Orthodox Christianity") that emerged in this period in the persons and theological positions of the Apostolic Fathers would eventually become the international Great Church. Proto-Orthodox Christianity placed importance on the sacrifice of Jesus on the cross as saving humanity, and described Jesus as the incarnated Son of God come to Earth. The 2nd and 3rd centuries AD saw a sharp separation between Jewish Christianity and Gentile Christianity, with the latter being derived from the teachings of the Apostle Paul. There was an explicit rejection of Second Temple Judaism and Jewish culture by the end of the 2nd century, with a growing body of anti-Jewish Christian literature. Many doctrinal variations in this era defy neat categorizations, as various forms of Christianity interacted in a complex fashion.

Leander of Seville (Spanish: Leandro de Sevilla; Latin: Leandrus; c. 534 AD – 13 March 600 or 601) was a Hispano-Roman Catholic prelate who served as Bishop of Seville. He was instrumental in effecting the conversion of the Visigothic kings Hermenegild and Reccared to Catholicism. His brother (and successor as bishop) was the encyclopedist Isidore of Seville.

Pope Victor I (died 199) was a Roman African prelate of the Catholic Church who served as the Bishop of Rome in the late second century. The dates of his tenure are uncertain, but one source states he became pope in 189 and gives the year of his death as 199. He was born in the Roman Province of Africa. He was later considered a saint. His feast day is celebrated on 28 July as "St Victor I, Pope and Martyr". He was of Berber origin.

Montanus (/mɒnˈteɪnəs/; Greek: Μοντανός) was the second century founder of Montanism and a self-proclaimed prophet. Montanus emphasized the work of the Holy Spirit, in a manner which set him apart from the Great Church.