Saint of the Week: Irenaeus
7/2/2025
St. Irenaeus
2nd Century A.D.
Bishop of Lyons and Martyr
Irenaeus of Lyons, an early and pivotal 2nd century theologian, is best known for his condemnation of heresies and work establishing traditions and doctrine of early Christianity. Born in Smyrna around 125 AD, he was well-traveled across Christendom spending most of his later years in Rome and Lyons. He also had ties to St. Polycarp, the famous martyr who allegedly studied under John the Evangelist and was Irenaeus’ tutor. This connected him directly with the Apostles and a solid education handed down from them. Known as the “Father of Tradition,” Irenaeus was a staunch defender of Christian faith against popular heresies of the time. Around 177 AD, his church in Lyons sent him to Rome to help settle theological disputes that had arisen due to heretical teaching. While away, all known Christians in Lyons were thrown into prison, among them, Lyon’s ill-fated Bishop Pothinus, whom Irenaeus was tapped to replace. Irenaeus was well loved by all who knew him and his preaching transformed the entire town into a “Christian city. Irenaeus wrote extensively about the heresies that troubled the Church particularly Montanism, Gnosticism, and Valentinianism, from which Irenaeus defended the faith by highlighting the heretics’ “absurd ideas” and exposing their errors and faulty logic. Irenaeus was highly influential in guiding the early Church along a straight and narrow path. For him, the Gospels were the best foundation for fighting heresy. He was the first to deem the four Gospels as canonical Scripture and attested to their authorship. They also served as the basis upon which he developed his writings. His most famous work, Adversus Haereses (“Against Heresies”), is the first work that cites virtually every book of early Christian writings that we deem the New Testament. He also wrote The Demonstration of the Apostolic Preaching. Irenaeus was martyred in 202 AD when Emperor Semptimus Severus issued a decree allowing pagans to take vengeance on Christians. In June of that year, assassins in Lyons, armed with daggers, stones, and clubs, roamed the streets and murdered Christians who refused to participate in their debauchery. Irenaeus was among those slain.
