Story

From Constantinople to Chalcedon

How a dispute about Mary's title became a permanent split over Christ's person.

Step 1
One Son, and a title for Mary
Nestorius resisted calling Mary Theotokos, God-bearer, because he thought it blurred the Son's humanity. Cyril heard a threat to the one subject of the incarnation. Both claimed Nicaea.
Nestorius Cyril of Alexandria Constantinople Alexandria Move the map here
Step 2
Two councils at Ephesus
In 431 Cyril's council deposed Nestorius before the Antiochenes arrived. A reunion formula in 433 bought a fragile peace. In 449 Dioscorus restored Eutyches and silenced Leo's Tome. Leo called that second meeting a robbery.
Cyril of Alexandria John of Antioch Dioscorus of Alexandria Leo I of Rome Theodosius II Ephesus Ephesus Ephesus II Move the map here
Step 3
Chalcedon, 451
Under Marcian and Pulcheria, bishops confessed Christ in two natures, without confusion or separation, and deposed Dioscorus. Egypt and much of Syria refused the definition. The split is still with the churches. It was not a debate about whether Christ was God.
Leo I of Rome Marcian Pulcheria Dioscorus of Alexandria Chalcedon Chalcedon Move the map here

One Son, and a title for Mary