Literally "universal" and commonly used to identify the general councils of the Church. With the rise of the movement for Christian unity, it has become synonymous with "striving for reunification" among the separated Churches of Christendom. (Etym. Latin oecumenicus; from Greek oikoumen_, the inhabited world.)
Following are the ecumenical councils of the Roman Catholic Church, with dates and a brief statement of their principal legislation.
1. Nicaea I (325) Condemned Arianism, defined that the Son of God is consubstantial with the Father, formulated the Nicene Creed.
2. Constantinople I (381) Condemned the Macedonians who denied the divinity of the Holy Spirit. Confirmed and extended the Nicene Creed.
3. Ephesus (431) Condemned Nestorianism, which held that there were two distinct persons in the Incarnate Christ, a human and divine. Defended the right of Mary to be called the Mother of God.
4. Chalcedon (451) Condemned Monophysitism or Eutychianism by defining that Christ had two distinct natures, and was therefore true God and true man.
5. Constantinople II (553) Pronounced against certain persons as infected with Nestorianism, notably Theodore of Mopsuestia, Theodoret of Cyrrhus and Ibas of Edessa.
6. Constantinople III (680-81) Defined against the Monothelites that Christ has two wills, human and divine.
7. Nicaea II (787) Condemned the Iconaclasts or Image-breakers and defined that sacred images may be honored without idolatry.
8. Constantinople IV (869-70) Condemned Photius as Patriarch of Constantinople.
9. Lateran I (1123) First general council in the West, endorsed the Concordat of Worms regarding the investiture of prelates.
10. Lateran II (1139) Took measures against the schism of the antipope Anacletus II and issued disciplinary decrees.
11. Lateran III (1179) Legislated against the Waldenses and Abligensians and decreed papal elections by two-thirds majority of cardinals at conclave.
12. Lateran IV (1215) Made reform decrees, ordered annual confession and Easter Communion, first officially used the term "transubstantiation."
13. Lyons I (1245) Condemned Frederick II for his persecution of the Church.
14. Lyons II (1274) Effected a temporary reunion of the Eastern churches with Rome and decreed that papal elections should begin ten days after the death of the Pope.
15. Vienne (1311-12) Suppressed the Knights Templar, sought aid for the Holy Land, defined the relation of the soul to the human body, and condemned the false mysticism of the Fraticelli, Dulcinists, Beghards, and Beguines.
16. Constance (1414-18) Issued reform decrees in "head and members," condemned Wyclif and Hus, and put an end to the Western Schism.
17. Florence (1438-45) Affirmed the papal primacy against Conciliarists, who said that a general council was superior to the Pope, and sought to effect a reunion of the Eastern Churches separated from Rome.
18. Lateran V (1512-17) Defined the relation of Pope to a general council, condemned philosophers who taught the human soul was mortal and only one for all mankind, and called for a crusade against the Turks.
19. Trent (1545-63) Called to meet the crisis of the Protestant Reformation; proclaimed the Bible and tradition as rule of faith, defined doctrine on the Mass, the sacraments, justification, purgatory, indulgences, invocation of saints, veneration of sacred images, issued decrees on marriage and clerical reform.
20. Vatican I (1869-70) Define the nature of revelation and faith, the relation of faith and reason, and papal infallibility; condemned pantheism, materialism, deism, naturalism, and fideism.
21. Vatican II (1962-65) Convoked by Pope John XXIII, "mainly to more effectively preserve and present the sacred deposit of Christian doctrine." Its sixteen documents reaffirmed the principles of Catholic faith and morality, and authorized numerous developments in the Eucharistic liturgy, the ritual of the sacraments, and in the Church's administrative structure.