Anyone who looks at the church today and craves the long-past glories of true faith ought to look at its actual history. The oft-reported stories of sexual and fiscal impropriety in the contemporary church are nothing new. The halcyon days when the church’s leaders were truly faithful are as imaginary as human potential and free will. The desire to make the church great again has to reckon with its actual history, including the lives of the saints.

Cyril of Alexandria is an exemplar. He is known as the prime proponent of a doctrine that asserted Jesus was both fully human and fully divine. But his pugnacity in Christological controversies led him to what modern sensitivities consider a long and sordid history before that fight. He is the ur-example of a Christian as both saint and sinner.

Our Cyril shouldn’t be confused with another well-known Cyril who was a missionary to the Slavs and gave us the Cyrillic alphabet. Our Cyril (AD 376-444) was archbishop of Alexandria, one of five centers of Christianity in the ancient church along with Jerusalem, Antioch, Constantinople, and Rome. Along with his African contemporary Augustine, Cyril led the fight for orthodoxy in response to teachings that weakened Christ’s work and dulled the church’s witness.

His pugnacity in Christological controversies led him to what modern sensitivities consider a long and sordid history before that fight.

Cyril’s fervor for pure explication of the gospel was present throughout his career. He wrote numerous exegetical works, including commentaries on the Pentateuch, Isaiah, and minor prophets. His greatest contribution, however, comes in his battle with Nestorius over Christ’s nature: How was the human Jesus who walked the paths of Judea also divine? How was the one who rules on high also the one who voiced a cry of dereliction from the cross.

Cyril asserted that both the divine and human are united and fully present in the person of Jesus: “I say that it is appropriate neither for the Logos of God apart from the humanity, nor for the temple born of the woman not united to the Logos, to be called Christ Jesus.” Even though Scripture sometimes speaks of one nature or the other, divine or human, Cyril argued that “he is not treated unjustly by either way of speaking, on account of the conjunction of the two [natures] into a unity.” Christ is and must be both born in Bethlehem and existing from the foundation of the world. Thus, for Cyril, what happens to Jesus as human also happens to God and vice versa. The theological term for this is the communication idiomatum, or the exchange of attributes.

Nestorius, the bishop of Constantinople, objected, citing Luke 2:52. After the incident of the boy Jesus in the temple, he “increased in wisdom and in years and in divine and human favor.” Nestorius inferred that “He is brought to perfection who increases little by little,” thus, that there is a separation present in Jesus. But Cyril countered that Jesus’ divinity could have easily happened without growth and change, but it would have necessitated “a monstrous affair and a violation of the words of the economy [of salvation].” In other words, Jesus’ increase happened because the divine took on the human fully. For an extended treatment of this important debate, see Jaroslav Pelikan’s The Christian Tradition, A History of the Development of Doctrine: 1 The Emergence of the Catholic Tradition (100-600).

Cyril and Nestorius were the Luther and Zwingli of their age, and their dispute has been an ongoing tug-of-war in the centuries since then. The proper term for this doctrine is “the hypostatic union of Christ.” Although the phrase didn’t appear in English until the seventeenth century, the idea was already present in the Apostles’ Creed, which confesses that the Son of God was “conceived by the Holy Spirit and born of the virgin Mary.” Cyril’s approach was grounded both in the Scriptures and in the church’s prior confessions.

In spite of his theological acumen, Cyril has plenty of strikes against him — at least to our contemporary standards of decency, our desire to acknowledge the marginalized and aggrieved, and our avoidance of the slightest strain of hypocrisy. Cyril accompanied his uncle Theophilus to a synod in Constantinople at which St. John Chrysostom was subjected to false accusations and deposed. He closed the Novatian churches, whose members were followers of a self-described antipope, and he expelled the Jews from Alexandria. In addition, Cyril has also been charged by historians today of having had a hand in the execution of the famous female philosopher, Hypatia of Alexandria.

Apart from the theological underpinnings in the church’s witness that are linked to Cyril’s work, most Christians today encounter him when they wonder why the date of Easter changes. Easter is always the first Sunday after the first full moon after the first day of spring. Cyril created an influential “Paschal table” which predicted the dates of Easter for a 19-year lunar cycle.

Cyril died in his late sixties in AD 444 but wasn’t officially named a saint by the Catholic church until 1982. He is regarded by the Roman church as Bishop, Confessor, Teacher of the Faith and Doctor of the Church. His feast day is celebrated on June 28.