CHURCH HISTORY: Ecumenical Councils

The idea of an ecumenical council is that it is a gathering of leaders of the whole church (oikoumene - inhabited world or household in Greek) to determine doctrine and/or practical matters. There were many councils in the ancient world and dispute about some of them being "ecumenical". The Eastern Orthodox churches hold to seven ecumenical councils. The Oriental Orthodox churches hold to just the first three councils. And the Roman Catholic church holds to twenty-one councils, and counting. Most Protestant churches would agree with either four or seven as being truly ecumenical.

Local bodies within the church would sometimes call for meetings. Those, more local, gatherings would often be called a synod.

First Council of Nicaea (325 CE) - against Arianism, homoousios (same substance as the Father), adopted Nicene Creed, and established date for Easter

First Council of Constantinople (381 CE) - against Arianism, against Apollinarism, and the divinity of the Holy Spirit, which required the rewording of the Nicean Creed into the Niceno-Constantinopolitan Creed

Council of Ephesus (431 CE) - against Nestorianism, against Pelagianism, and affirmed Mary as the Theotokos

Council of Chalcedon (451 CE) - against monophysitism, adopted Chalcedonian Creed which describes the union of Christ's two natures, and elevated Constantinople and Jerusalem to patriarchates.