Eutyches

Eutyches was a theologian who lived in the 5th century CE. He was a presbyter and archimandrite in Constantinople. Eutyches is primarily known for his Christological views, which became the subject of significant controversy. He taught that in Christ there were two natures before the union, but only one nature after the union. This concept became known as Monophysitism, though Eutyches himself may not have used this specific term to describe his theology.

His teachings were condemned by the Synod of Constantinople in 448 CE. Eutyches appealed this decision to the Emperor Theodosius II, who convened a council in Ephesus in 449 CE, often referred to as the Second Council of Ephesus or the "Robber Synod." This council, largely influenced by Eutyches' supporters, reinstated him and condemned his opponents. However, this outcome was not recognized by the Western Church or many Eastern bishops.

The following year, 451 CE, the Council of Chalcedon was convened. This council formally rejected Eutyches' teachings and declared that Christ has two natures, divine and human, united in one person without confusion, change, division, or separation. This Chalcedonian definition became the orthodox Christological stance for most of Christianity. Eutyches was subsequently excommunicated and exiled, and his theological position continued to be a source of division within the church, leading to the formation of Non-Chalcedonian churches.