What Is an Ecumenical Council?

When the earliest Church faced a question that threatened to divide it — whether Gentile converts had to keep the Law of Moses — the apostles and elders did not decide privately but gathered in council at Jerusalem, and issued their decision with a remarkable formula: "For it seemed good to the Holy Ghost, and to us" (Acts 15:28). That council in Acts 15 is the model for every later one. The Church discerns the truth together, in the confidence that the Spirit whom Christ promised will "guide you into all truth."

A council (or synod) is simply an assembly of bishops. Local councils met constantly in the early centuries to handle regional affairs. An ecumenical council is different in scope: it represents the whole Church and treats questions on which the whole Church must speak with one voice — usually a doctrinal crisis that ordinary teaching could not resolve. Between 325 and 787 the Orthodox Church recognizes seven such councils.

It is tempting to think a council is authoritative because an emperor summoned it, or because a great many bishops attended, or because it was ratified by a leading see. Orthodoxy holds that none of these, by itself, is decisive. The deepest answer is reception: a council proves to be ecumenical when the whole Church — bishops, clergy, and faithful together, over time — recognizes in its decrees the unchanging faith handed down from the apostles.

History makes the point sharply. In 449 a large council met at Ephesus with imperial backing and every outward mark of authority, yet it endorsed heresy; the Church rejected it, and it is remembered not as a council but as the "Robber Council." Convocation and attendance could not make it true. By contrast, the councils the Church did receive were vindicated precisely because the body of the faithful recognized their own faith in them. This is the Orthodox instinct of conciliarity: the truth is guarded by the whole Church, not by any office within it acting alone.

An ecumenical council does not invent new doctrine or improve upon the faith. Its work is to guard what was already believed by drawing a clear line where a heresy has blurred one — and, when necessary, to forge precise language for it. The word homoousios ("of one essence") and the title Theotokos ("Mother of God") were not additions to the Gospel but fences built to protect it. Councils also issue canons, the practical rules that order the Church's common life.

So the councils belong to the same living Tradition as Scripture and the Creed; they are how the Church, in a crisis, states plainly what she has always held. Their definitions carry the weight of dogma — settled, binding, not up for renegotiation. And their number is not, in principle, closed: Orthodoxy confesses seven ecumenical councils not because more are forbidden but because these seven are the ones the whole Church has received.