Today we celebrate the feast of St. Leo the Great. Leo is best known as the pope who stared down Attila the Hun, thus delaying the fall of the Western Empire to the barbarians. However, I would argue that his actions against Attila are insignificant compared to his work in the area of Christology. Soon after Leo’s death the Western Empire did fall, but Leo’s declaration of the two natures of Christ still guides the Church to a proper understanding of Christ today.

After the legalization of Christianity under the Emperor Constantine in the early 4th century, the Church was engaged in a very public and very painful debate to answer the question that Jesus asked his apostles three centuries earlier: “Who do you say that I am?” Peter’s answer of “The Christ, the Son of the living God” needed further elaboration. Was Christ God? If so, was he still a man? Or was he some combination of the two, making him a third type of being? How can someone be both God and man at the same time? And if Jesus of Nazareth is God, what did that say about Mary? Was she just the mother of Christ or the mother of God? If Jesus is God, does that mean that God “died” on the cross? These are serious questions, and the answers the Church gives has major implications for the life of all Christians.

This was the situation in which Leo was Pope. After the Council of Ephesus in 431 the East was furiously debating the exact relationship between Christ’s human nature and his divine nature (the West was much more conservative in orientation and usually didn’t have these types of debates at this time), and their theological debates were not without major political ramifications (as is usually the case with theological debates). Into this mix Leo produced his famous “Tome” which clearly declared that Christ was a human person who had both divine and human natures and that there was no confusion between these two natures.

After reading this Tome out during the Council of Chalcedon, the Council Fathers proclaimed:

This is the faith of the fathers, this is the faith of the Apostles. So we all believe, thus the orthodox believe. Anathema to him who does not thus believe. Peter has spoken thus through Leo!

It was St. Peter who first answered Christ’s famous question, “Who do you say that I am?” and it fell to St. Peter’s successor to give us a better understanding of that answer, an understanding that still forms the basis for orthodox Christology today. If we want to know who Jesus is, we need to follow the confession of Peter and his successor, St. Leo.

St. Leo the Great, pray for us!