St. Leo the Great: The pope who clarified the humanity and divinity of Christ

Throughout the last two millennia, the Catholic Church has only granted the title “doctor of the Church” to 38 saints, one of whom we celebrate today on Nov. 10: St. Leo the Great, the 45th bishop of Rome.

Pope Leo I, who was the first pope to be remembered posthumously as “the Great,” began his papacy in 440 and served until his death in 461. During his pontificate, he worked to clarify doctrines related to Christ’s human and divine natures.

The pontiff was a “pope-theologian, but he’s also known as a remarkable bishop,” Thomas Clemmons, a professor of Church history at The Catholic University of America, told EWTN News, adding that “theologian popes are rare.”

St. Leo’s papacy began nine years after the Council of Ephesus, which condemned Nestorius and the heresy of Nestorianism, leading many of Nestorius’ followers to schism. The heresy rejected the close union of Christ’s human and divine natures and rejected the Marian title of “Theotokos,” or God-bearer, claiming that Mary only gave birth to Christ’s human nature.

Rising out of the Nestorian schism were more Christological conflicts over the relationship between Christ’s humanity and divinity. Eutyches, an opponent…