Irenaeus was born around the year 130, in Smyrna, Asia Minor, today part of Turkey. As a boy, he heard the preaching of Polycarp, bishop of that city, who had been a direct disciple of the apostle John. That memory would mark his entire life.
As an adult, Irenaeus settled in Lyon, in Roman Gaul, present day France, where he served as a presbyter of the local church. There he witnessed firsthand the cost of the Christian faith before the Roman Empire.
In 177, a wave of persecution struck Lyon under the emperor Marcus Aurelius. Bishop Pothinus died as a martyr, and Irenaeus, who at that time was in Rome as an emissary of the church, returned to take up the position of second bishop of Lyon.
As a pastor, Irenaeus confronted Gnosticism, a movement that promised salvation through secret knowledge and despised material creation. He responded with the work Against Heresies, written around 180, patiently exposing the errors of these doctrines.
In that work, he argued that the Christian faith rests on the Scriptures received from the apostles and on the historical succession of bishops who guarded them, not on private revelations. He was one of the first to explicitly recognize the four Gospels as an authoritative collection.
Not all of Irenaeus’s arguments have stood the test of time. To refute the Gnostics, he argued, relying on a tradition attributed to presbyters connected to the apostle John, that Jesus had lived to nearly fifty years of age, a calculation historians today consider mistaken. Irenaeus also held the belief, common among Christians of his time, in a literal thousand year reign of Christ on earth, an idea that most of the church would later abandon.
Irenaeus also acted as a peacemaker. When Pope Victor I threatened to break communion with churches in Asia Minor over the date of Easter, he intervened, urging moderation, consistent with the meaning of his own name, which in Greek points to peace, something the historian Eusebius already noted in his Chronicle.
He died around 202, in Lyon. A later tradition regards him as a martyr, though the historical sources do not allow confirmation of the exact circumstances of his death.
Irenaeus’s legacy spans the centuries: his defense of historical revelation, the biblical canon, and the unity of the church continues to guide Christianity in the face of doctrines foreign to the gospel, in his time and in ours.
