The Ecumenical Councils

The Seven Ecumenical Councils, as commonly understood, are:

1) First Council of Nicaea (325 A.D.) - Emperor Constantine (the State) forces a council of Bishops. Church Bishops declared that God the Father and Jesus Christ the Son of God "of the same substance as the Father".
2) First Council of Constantinople (381) - Church declares that the Holy Ghost is of the same substance as the Father and the Son.  Official trinity completed.  "One God in three persons"
3) Council of Ephesus (431)
4) Council of Chalcedon (451)
5) Second Council of Constantinople (553)
6) Third Council of Constantinople (680)
7) Second Council of Nicaea (787)