Born around 125 AD in the city of Smyrna, unlike most of the early “church fathers” Irenaeus was brought up a Christian rather than converted. During the persecutions of Roman emperor Marcus Aurelius, the brilliant “philosopher-king” who had some intellectual concerns with the Christians, Irenaeus was made a priest of Lugdunum in Gaul.

Little is known of the details of his life after Irenaeus got promoted, but it seems he divided his activities between the duties of a pastor to his flock and of a missionary. Mostly, he wrote, virtually all of his works are diatribes against the heresy of Gnosticism, a fashionable movement in the rapidly expanding Catholic Church that espoused dualism and situational ethics undertaken by each individual. His best known rant, Adversus Haereses (“Against Heresies”), is a detailed attack on Gnosticism that emphasized the elements of Catholicism: the episcopate, scriptures and religious ritual. Irenaeus argued that the only “safe” guide to interpretation of the holy writings came from the bishops, who traced their lineage direct to the first apostles. His polemical works are credited with establishing the orthodoxy of Christianity and the evolving doctrine of the primacy of the Papal See.

The last record of Irenaeus is dated to 190 or 191 when he exerted influence on Pope Victor I not to excommunicate Christian communities in Asia Minor which had fallen into the practice of the Quartodeciman celebration of Easter. Irenaeus died c. 200 AD. Although there is a tradition of him being martyred, there is no actual evidence that he died from anything other than natural causes.