the 21 Church Councils

Nicaea I

The first ecumenical council held in 325 that condemned Arianism, defined the consubstantiality of the Father and the Son, fixed the date for Easter, and began the formulation of the Nicene-Constantinopolitan Creed.

Arianism

A heresy that denied the divinity of Christ.

Nicene-Constantinopolitan Creed

A statement of faith formulated to clarify the beliefs about the nature of God and Christ established in the Nicaea I and Constantinople I councils.

Constantinople I

The second ecumenical council held in 381 that reaffirmed the decisions of Nicaea I and condemned Macedonianism.

Macedonianism

A heresy that denied the divinity of the Holy Spirit.

Ephesus

The third ecumenical council held in 431 that condemned Nestorianism and confirmed Mary as Theotokos (Mother of God).

Nestorianism

A heresy that denied the unity of the divine and human in Christ.

Chalcedon

The fourth ecumenical council held in 451 that condemned Monophysitism and affirmed Christ's two natures.

Monophysitism

A heresy that denied Christ's human nature, claiming that He had only a divine nature.

Lateran I

The first Lateran Council held in 1123 that confirmed the Concordat of Worms, resolving disputes over investiture.

Lateran III

The third Lateran Council held in 1179 that regulated papal elections and condemned Waldensianism and Albigensianism.

Transubstantiation

The doctrine explaining the Real Presence of Christ in the Eucharist, established at Lateran IV.

Trent

The ecumenical council that took place between 1545 and 1563, affirming key Catholic doctrines and initiating the Counter-Reformation.

Papal infallibility

The doctrine defined at Vatican I asserting that the pope is incapable of error in pronouncements on faith and morals.

Vatican II

The ecumenical council from 1962-1965 that addressed renewal and reform in the Church for a modern context.

Concordat of Worms

An agreement between the Pope and the Emperor to resolve the investiture controversy.

Pelagianism

A heresy that held that man could earn his own salvation through natural powers.

Real Presence

The doctrine that Jesus Christ is truly present in the Eucharist.

Ecumenical council

A conference of ecclesiastical authority in the Christian Church.

Infalable statements

Pronouncements made by the pope that are considered free from error in matters of faith and morals.

Great Schism

The split that resulted in three rival claimants to the papacy prior to the Constance council.