St. Irenaeus is a 2nd-century bishop and writer revered by both Catholics and Orthodox Christians and known for refuting the heresies of Gnosticism with a defense of both Christ’s humanity and divinity.
While some of St. Irenaeus’ most important writings have survived, the details of his life are not as well preserved. He was born in the Eastern half of the Roman Empire, likely in the coastal city of Smyrna, in what is now Turkey, around the year 140 A.D.
As a young man, he heard the preaching of the early Christian bishop St. Polycarp, who had been personally instructed by the Apostle John. Irenaeus became a priest, serving the Church in the region of Gaul, in what is now France, during a difficult period in the late 170s.
During this time of state persecution and doctrinal controversy, Irenaeus was sent to Rome to provide Pope St. Eleutherius with a letter about the heretical movement known as Montanism.
After returning to Lyon, Irenaeus became the city’s second bishop, following the martyrdom of his predecessor St. Pothinus.
In the course of his work as a pastor and evangelist, the second bishop of Lyon came up against heretical doctrines and movements that insisted that the material world was evil and not part of God’s original plan.
Irenaeus recognized this movement, in all its forms, as a direct attack on the Catholic faith. He rebutted the Gnostic errors in his lengthy book “Against Heresies,” which is still studied today for its historical value and theological insights.
A shorter work, the “Proof of the Apostolic Preaching,” contains Irenaeus’ presentation of the Gospel with a focus on Jesus Christ’s fulfillment of Old Testament prophecies. Several of his other works are now lost, though a collection of fragments from them has been compiled and translated.
Irenaeus died in Lyon around 202, when Emperor Septimus Severus ordered the martyrdom of Christians.
The U.S. bishops voted in 2019 in favor of having St. Irenaeus named a Doctor of the Church at the request of Cardinal Philippe Barbarin, the then archbishop of Lyon, and sent their approval to the Vatican for the pope’s consideration.