What is an ecumenical council?

An ecumenical council is a solemn assembly of the world's Catholic bishops acting together with and under the pope. It addresses major questions of doctrine, discipline, worship, or the Church's mission.

Who has authority at a council. Christ entrusted His authority to the apostles as a body, with Peter as their head. Their successors are the bishops, who form a college with the pope, Peter's successor, as its head (CCC 880-881). An assembly becomes an ecumenical council through papal convocation or recognition, and its decrees require the pope's confirmation. The college of bishops cannot exercise supreme authority apart from its head (CCC 883-884).

What councils do. Councils commonly clarify disputed doctrines, condemn serious errors, establish Church discipline, or guide pastoral action. The Council of Nicaea in 325 defended the full divinity of Christ. The Council of Ephesus in 431 affirmed that Mary is truly the Mother of God because her Son is one divine Person. The Council of Trent responded to the Protestant Reformation, and the First Vatican Council defined papal primacy and infallibility. The Catholic Church commonly recognizes twenty-one ecumenical councils, ending most recently with the Second Vatican Council.

How authoritative their teachings are. A council can teach infallibly when, united with the pope, the bishops definitively proclaim a doctrine of faith or morals for the whole Church (CCC 891). Councils also issue disciplinary rules, pastoral guidance, and reforms that are authoritative without being irreformable dogmas. A temporary fasting rule, administrative policy, or liturgical discipline can change. A solemn definition concerning Christ's divinity cannot.

Not every sentence in a conciliar document carries the same doctrinal weight. Catholics read each statement according to its language, purpose, and relationship to Scripture and Tradition. Calling a council pastoral does not make its teaching optional. Authentic non-definitive teaching still calls for religious submission of mind and will (CCC 892).

Why councils matter. Councils show the Church discerning grave questions in communion rather than through isolated private interpretation. At the Council of Jerusalem, the apostles and elders met to settle a dispute, then announced, “It is the decision of the Holy Spirit and of us” (Acts 15:6, 28). That biblical pattern continues in the Church.

When reading a council, begin with its actual documents and a reliable Catholic guide. Avoid judging it only by slogans, later controversies, or abuses committed in its name.