Bishop Irenaeus of Lyons (d. 200)
Irenaeus was born in Smyrna around 120. As a young man, he studied the Christian faith under Smyrna’s bishop Polycarp, who was a disciple of the apostle John. Around 150, Polycarp sent Irenaeus to Lyons in southern Gaul (modern France) to serve as an elder among the Christians from Asia Minor. Iranaeus served as the bishop of Lyons for twenty-two years, from 178 to 200. Writing in Greek, he was a significant writer against false teaching and authored Against Heresies, a five-volume defense of the Christian faith. Irenaeus was one of the first theologians to use the principle of apostolic succession to refute his opponents and was one of the first to write a systematic Christian theology. He was possibly martyred under the rule of emperor Septimus Severus (193-211) in 200.