Catholic ecumenical councils

According to the Catholic Church, a Church Council is ecumenical ("world-wide") if it is "a solemn congregation of the Catholic bishops of the world at the invitation of the Pope to decide on matters of the Church with him". The wider term "ecumenical council" relates to Church councils recognised by both Eastern and Western Christianity.

In Catholicism, in addition to ecumenical Councils, there are "particular Councils". Current Canon Law recognises two kinds of particular Councils: plenary councils involve the bishops of an episcopal conference (usually a single country), while provincial councils involve the bishops of an ecclesiastical province.

The Catholic Church recognizes as ecumenical 21 councils occurring over a period of some 1900 years. The ecumenical nature of some Councils was disputed for some time but was eventually accepted, for example the First Lateran Council and the Council of Basel. A 1539 book on ecumenical councils by Cardinal Dominicus Jacobazzi excluded them, as did other scholars.

The first few centuries did not know large-scale councils; they were feasible only after Emperor Constantine granted the Church freedom from persecution. As a result, the Council of Jerusalem or Apostolic Council, held in Jerusalem around AD 50 and described in Acts of the Apostles chapter 15, is not an ecumenical Council, even though most Christian denominations consider that it expresses a key part of Christian doctrine and moral teaching.

These comprised the hierarchs of the undivided Church (i.e. both East and West), and are accepted as authoritative, not only by Catholics, but also by the Eastern Orthodox Church and many Protestant denominations.

The First Council of Nicaea (20 May – 25 July? 325) formulated the original Nicene Creed. Most importantly, the council defined the equality of God the Father and Christ, his son. It taught that Jesus was of the same substance as God the Father and not just merely similar. By defining the nature of the divinity of Jesus, the council did not solely rely on the Bible but jointly gave it a binding interpretation. The council issued 20 canons and repudiated Arianism.

The First Council of Constantinople defined in four canons the Nicene Creed, which is still used in the Catholic Church. Most importantly, it defined the divinity of the Holy Spirit. The council met from May until July 381 during the pontificate of Pope Damasus I and issued four canons.

The Council of Ephesus proclaimed the Virgin Mary as the Theotokos (Greek Η Θεοτόκος, "Mother of God" or "God-bearer"). The council met in seven sessions during the pontificate of Pope Celestine I from 22 June until 17 July 431. It rejected Nestorianism.