Saint Irenaeus of Lyon

Saint Irenaeus was bishop of Lyon in Gaul in the second century, a disciple of Saint Polycarp of Smyrna and one of the first great theologians of the Church. He defended the apostolic faith against Gnosticism. His liturgical memorial falls on June 28.

He came from Asia Minor and was most probably born in Smyrna, today Izmir in Turkey. The year of his birth is unknown: Benedict XVI pointed to the years between 135 and 140, and the Italian Roman Missal to about 130. In his youth he listened in Smyrna to Bishop Polycarp, a disciple of Saint John the Apostle. What we know of his life comes mainly from his own words, handed down by Eusebius of Caesarea.

It is not known when he came to Gaul. In 177 he was a priest of the Church of Lyon, and that year the community sent him to Rome with a letter to Pope Eleutherius. This journey spared him the persecution under Emperor Marcus Aurelius, in which at least forty-eight martyrs died. Among them was the ninety-year-old Bishop Pothinus, who died in prison, worn out by ill-treatment. On his return Irenaeus succeeded him in the episcopal see of Lyon.

His name comes from the Greek word for peace, and the Italian Missal calls him a man of peace in name and in deed. When Pope Victor I excommunicated the Churches of Asia Minor, which by an ancient custom celebrated the Pasch on the fourteenth day of the month of Nisan, Irenaeus, although he himself held that the Resurrection should be celebrated on Sunday, wrote to him not to cut off whole Churches. He recalled that Polycarp and Pope Anicetus, though they did not agree, had kept the peace.

His principal work, the five books Against Heresies, refutes the teachings of the Gnostics, who claimed that only the initiated knew the true meaning of the faith. Irenaeus showed that the apostolic Tradition is public, handed on through the succession of bishops and one throughout the Church, and he took as its measure the Church of Rome, founded by Peter and Paul. His Demonstration of the Apostolic Preaching has also survived, which, according to Benedict XVI, can be called the oldest catechism. It was Irenaeus who wrote that the glory of God is man fully alive, and the life of man is the vision of God.

The year and the circumstances of his death are unknown. According to Benedict XVI his ministry ended about 202 or 203, perhaps with martyrdom. Saint Jerome was the first to call him a martyr, and the Roman Martyrology says that he is said to have been crowned with glorious martyrdom. The liturgy honors him as bishop and martyr.

Irenaeus has been venerated as a saint since antiquity, without a formal canonization. On January 21, 2022, Pope Francis, in an apostolic letter, declared him a Doctor of the Church with the title Doctor of Unity. He wrote in it that Irenaeus, who came from the East and exercised his episcopal ministry in the West, became a spiritual and theological bridge between Eastern and Western Christians.