Saint Irenaeus (c. 130 – c. 200) was born in the East, most lIkely in Smyrna, whose first bishop was Polycarp, a disciple of Saint John the Apostle.
Irenaeus became a priest and later Bishop of Lyons, an important trading center in Gaul of the western Roman empire.
Despite his dislike of the teachings of the Montanist and other heretical sects, he often favoured peacemaking and unity instead of persecution in order to win heretics back to the fulness of the Faith.
Nonetheless, through his great works Adversus Haereses and the Demonstration of Apostolic Preaching, he refuted Gnosticism. He emphasized Christian monotheism, our Lord’s Incarnation, and advocated the creation of a Canon of Scripture as well as protection of the tradition of apostolic succession of the episcopate.
“Continue thou in the things which thou hast learned and hast been assured of: knowing of whom thou hast learned them, and that from a child thou hast know the holy Scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus.” (2 Timothy 3:14, from the day’s mass propers)