Irenaeus of Lyon

Irenaeus of Lyon was a Greek bishop of the second century. He was born in Smyrna, today’s İzmir, and learned from Saint Polycarp. He became the second bishop of Lyon after the persecution of 177, and around 180 he wrote Against Heresies, his book defending the apostles’ teaching against the Gnostics.

Irenaeus of Lyon was one of the greatest theologians of the second century — and, for those of us in this corner of Turkey, a man with deep roots in our own soil, for he grew up in Smyrna, modern İzmir, as a disciple of the great Saint Polycarp.
As a boy, Irenaeus listened to Polycarp, who had himself known the Apostle John — so Irenaeus stood just two steps from the apostles themselves. He carried that living memory west to Gaul, where he became bishop of Lyon and wrote his famous work “Against Heresies,” a powerful defence of the true faith against the Gnostics and one of the most important Christian writings of its age.
Irenaeus was also a peacemaker — his name fittingly means “peaceful.” When the bishop of Rome threatened to cut off the churches of Asia over the date of Easter, it was Irenaeus who stepped in and urged tolerance, helping to heal the breach. He is remembered as a bridge between East and West, and between the apostolic age and the Church that followed.
The İzmir where Irenaeus grew up — ancient Smyrna, one of the Seven Churches — is one of my favourite cities to guide. To discover it with a local guide, reach me through toursaroundturkey.com.

Where Was Irenaeus of Lyon Born and Who Taught Him?

Irenaeus was born in Smyrna, probably around the year 130, and his teacher was Polycarp, the old bishop of the city. He seems to have grown up in a Christian family, which was not so usual in those days.

Many years later, as a bishop far away in Gaul, he still remembered the very place where Polycarp used to sit and teach. He remembered how the old man came in and went out, and how he told about his talks with John. Smyrna was one of great cities of Roman Asia.

How Did Irenaeus Become Bishop of Lyon?

Irenaeus became bishop after the persecution of 177, when Pothinus, the first bishop of Lyon, died in prison. Lyon was Lugdunum in those days, a Roman city in Gaul. A number of its Christians were Greeks from Asia Minor, and Pothinus came from there too.

Irenaeus was still a priest when the trouble began. The clergy of Lyon sent him to Rome with a letter for Eleutherius, the bishop of Rome, about the Montanist movement that had started in Phrygia. When he came back, he took the place of Pothinus. The Christians of Lyon also wrote a letter about their martyrs to the churches of Asia Minor, and that letter has survived until today.

What Is Against Heresies by Irenaeus?

Against Heresies is the main book of Irenaeus, written in Greek around 180 in five volumes against the teaching of the Gnostics. Its full title is On the Detection and Overthrow of the So-Called Gnosis. The Gnostics said that Jesus left a secret knowledge for a few chosen people, Irenaeus answered that the truth is open for everybody. It is in the Scriptures, in the teaching of the apostles, and in the bishops who followed them.

He is also one of the first writers who counts the four Gospels, Matthew, Mark, Luke and John, as the Gospels of the Church. Most of the Greek text is lost, but a full old Latin translation survived.

Why Does İzmir Remember Irenaeus?

İzmir remembers Irenaeus of Lyon as a son of old Smyrna and as the pupil who carried the memory of Polycarp to the West. He was buried in Lyon, in a church that later took his name. In 2022 Pope Francis named him a Doctor of the Church and gave him the title Doctor of Unity, which fits a man of peace.

To feel his world in İzmir, I recommend my guests to start from the agora of Smyrna and the Church of Saint Polycarp. Read my post on Saint Polycarp of Smyrna first, then the story of Irenaeus makes more sense. The city itself is in my post about the Church of Smyrna.

Frequently Asked Questions

Who was Irenaeus a disciple of?

Irenaeus was a disciple of Saint Polycarp, the bishop of Smyrna, whom he heard as a boy in what is now İzmir. Polycarp had known the Apostle John, and that link is why people trusted Irenaeus as a witness of the apostles’ teaching.

What is Against Heresies about?

Against Heresies is a five-volume book written around 180 against the Gnostics. Irenaeus describes their teachings and answers them with the Scriptures and the apostles’ tradition. Until the books of Nag Hammadi were found in Egypt in 1945, it was the best description of Gnostic belief that survived.

How did Irenaeus of Lyon die?

We do not know the date or the way. It was at the end of the second century or the beginning of the third. Some churches count him as a martyr, but this comes from later tradition. He was buried in Lyon.