First seven Ecumenical Councils
In the history of Christianity, the first seven ecumenical councils, from the First Council of Nicaea (325) to the Second Council of Nicaea (787), represented an attempt to reach an orthodox consensus...
First Council of Nicaea
The First Council of Nicaea (/naɪˈsiːə/; Greek: Νίκαια [ˈni:kaɪja]) was a council of Christian bishops convened in Nicaea in Bithynia by the Roman Emperor Constantine I in AD 325. This first ecum...
Fifty Bibles of Constantine
The Fifty Bibles of Constantine were Bibles in Greek language commissioned in 331 by Constantine I and prepared by Eusebius of Caesarea. They were made for the use of the Bishop of Constantinople in t...
First Council of Constantinople
The First Council of Constantinople (Greek: Κωνσταντινούπολις Konstantinoúpolis) was a council of Christian bishops convened in Constantinople (present-day Istanbul in Turkey) in AD 381 by the Rom...
First Council of Ephesus
The Council of Ephesus was a council of Christian bishops convened in Ephesus (near present-day Selçuk in Turkey) in AD 431 by the Roman Emperor Theodosius II. This third ecumenical council, an effor...
Council of Chalcedon
The Council of Chalcedon (/kælˈsiːdən/ or /ˈkælsɨdɒn/) was a church council held from October 8 to November 1, AD 451, at Chalcedon (a city of Bithynia in Asia Minor), on the Asian side of the Bosporu...
Second Council of Constantinople
The Second Council of Constantinople is the fifth of the first seven ecumenical councils recognized as such by both West and East. Eastern Orthodox, Catholics, and Old Catholics unanimously recognize ...
Three-Chapter Controversy
The Three-Chapter Controversy, a phase in the Chalcedonian controversy, was an attempt to reconcile the Non-Chalcedonian Christians of Syria (Syriac Orthodox Church) and Egypt (Coptic Orthodox Church)...
Second Council of Nicaea
The Second Council of Nicaea is recognized as the seventh of the first seven ecumenical councils by both West and East. Orthodox, Catholics, and Old Catholics unanimously recognize it; Protestant opi...
Apollinaris of Laodicea
Apollinarius "the Younger" (died 390) was a bishop of Laodicea in Syria. He collaborated with his father Apollinarius the Elder in reproducing the Old Testament in the form of Homeric and Pindaric poe...
Church of the East
The Church of the East (Syriac: ܥܕܬܐ ܕܡܕܢܚܐ ʿĒ(d)tāʾ d-Maḏn(ə)ḥāʾ), also known as the Nestorian Church, is a historical Christian church within of the Syriac tradition of Eastern Christianity. Ori...
Caelestius
Caelestius (or Celestius) was the major follower of the Christian teacher Pelagius and the Christian doctrine of Pelagianism, which was opposed to Augustine of Hippo and his doctrine in original sin, ...
Eunomius of Cyzicus
Eunomius (Εὐνόμιος) (died c.393), one of the leaders of the extreme or "anomoean" Arians, who are sometimes accordingly called Eunomians, was born at Dacora in Cappadocia early in the 4th century.He s...
Third Council of Constantinople
The Third Council of Constantinople, counted as the Sixth Ecumenical Council by the Orthodox Church, the Catholic Church and other Christian groups, met in 680/681 and condemned monoenergism and monot...
Patriarch Pyrrhus of Constantinople
Pyrrhus was the Ecumenical Patriarch of Constantinople from 20 December 638 to 29 September 641, and again from 9 January to 1 June 654.He was a supporter of Monotheletism, a christological doctrine p...
Sergius I of Constantinople
Sergius I (d. 9 December 638 in Constantinople) was the Ecumenical Patriarch of Constantinople from 610 to 638. He is most famous for promoting Monothelite Christianity, especially through the Ecthesi...
Chalcedonian Creed
The Chalcedonian Definition (also Confession or Creed of Chalcedon) was adopted in A.D. 451 at the Council of Chalcedon in Asia Minor. That council was the fourth of the first seven Ecumenical Council...
Nestorianism
Nestorianism is a Christological doctrine that emphasizes the disunion between the human and divine natures of Jesus. It was advanced by Nestorius (386–450), Patriarch of Constantinople from 428–431,...
Cyrus of Alexandria
Cyrus of Alexandria was a Melchite patriarch of the Egyptian see of Alexandria in the 7th century, one of the authors of Monothelism and last Byzantine prefect of Egypt; died in Alexandria March 21, 6...
Macarius of Antioch
Macarius of Antioch was Patriarch of Antioch in the 7th century, deposed in 681. His title seems to have been a purely honorary one, for his patriarchate lay under the dominion of the Saracens, and he...
Constantine I and Christianity
While the Roman Emperor Constantine the Great (reigned 306–337) ruled, Christianity began to transition to the dominant religion of the Roman Empire. Historians remain uncertain about Constantine's re...
Pelagius
Pelagius (fl. c. 390-418) was a British-born ascetic moralist, who became well known throughout ancient Rome. He opposed the idea of predestination and asserted a strong version of the doctrine of fre...
Primacy of the Roman Pontiff
The primacy of the Bishop of Rome is an ecclesiastical doctrine concerning the respect and authority that is due to the Bishop of Rome from other bishops and their sees. Together with the Filioque c...
Nicene Creed
The Nicene Creed (Greek: Σύμβολον τῆς Νίκαιας, Latin: Symbolum Nicaenum) is a profession of faith widely used in Christian liturgy.It is called Nicene /ˈnaɪsiːn/ because originally adopted in the cit...
Development of the Christian biblical canon
The Christian biblical canons are the books Christians regard as divinely inspired and constituting a Christian Bible. Books included in the Christian biblical canons of both the Old and New Testament...
Arius
Arius (Ancient Greek: Ἄρειος, AD 250 or 256–336) was an ascetic Christian presbyter of Libyan birth, possibly of Berber extraction, and priest in Alexandria, Egypt, of the church of the Baucalis....
Schism of the Three Chapters
The Schism of the Three Chapters was a schism that affected the Catholic Church in North Italy lasting from 553 to 698 AD, although the area out of communion with Rome contracted throughout that time....
Council of Ephesus
The Council of Ephesus was a council of Christian bishops convened in Ephesus (near present-day Selçuk in Turkey) in AD 431 by the Roman Emperor Theodosius II. This third ecumenical council, an effor...
Theodore of Mopsuestia
Theodore the Interpreter (ca. 350 – 428) was bishop of Mopsuestia (as Theodore II) from 392 to 428 AD. He is also known as Theodore of Antioch, from the place of his birth and presbyterate. He is...