councils of Nicaea I (325 CE) concerning Arianism, Constantinople I (381 CE) concerning the Nicene Creed and the Arian controversy, Ephesus (431 CE) concerning Nestorianism, Chalcedon (451 CE) concerning Christology, Constantinople II (553 CE) concerning the "Three Chapters", Constantinople III (681 CE) concerning monoenergism and monothelitism, and Nicaea II (787 CE)