In the line of St John

The life of St Irenaeus was almost within touching distance of the disciples: he was a follower of St Polycarp, who himself learnt at the feet of St John. Born around 125, possibly in modern-day Turkey, to a Christian family, Irenaeus became Bishop of Lyons. He is best known for his writings, which were principally directed against the Gnostic heresy.

Gnostic deceptions

The Gnostic movement, known as Valentinianism, achieved considerable success in the 2nd century. Like all Gnostic systems, it was elitist and bafflingly complex.

In Against Heresies, Irenaeus warned his readers against the seductions of Gnostic thought. Irenaeus was concerned to expose the Gnostics’ thought, as well as to argue with it, for, as he once said, “Error never shows itself in its naked reality, in order not to be discovered. On the contrary, it dresses elegantly, so that the unwary may be led to believe that it is more truthful than truth itself.”

Lasting relevance

In Against Heresies, Irenaeus stressed that the authority of bishops came from Christ via the apostolic succession. It is one of several doctrines which Irenaeus helped to cement. His influence can be seen, for instance, in Pius IX’s declaration of the Immaculate Conception in 1854.

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