Council of Chalcedon: fourth of the seven Ecumenical Councils in which Christian doctrine was established (451).
- Organized, on behalf of his wife Pulcheria, by the emperor Marcianus, who was to succeed to the throne and wanted an end to the theological debate inaugurated at Ephesus;
- recognized by pope Leo I the Great;
- Jerusalem recognized as fifth patriarchate;
- discussion of the teachings of the archimandrite Eutyches;
- it is agreed that Christ's two natures are/were never fused, changed, divided, or separated;
- dogma that Jesus is and has always been fully human and fully divine;
- condemnation of Nestorius and Eutyches;
- the results are unacceptable to the theologians from Alexandria, and this results in the creation of the Orthodox Churches of the Eat (e.g., the Coptic Christianity in Egypt and the Armenian Church).