St. Irenaeus was one of the most important Early Church Fathers of the 2nd century AD. His life reveals the cosmopolitan nature of the Roman Empire at the height of its power. St. Irenaeus was bishop of Lyons, in Southern France, though he appears to have grown up in Smyrna, in modern-day Turkey. There Irenaeus had personal contact with St. Polycarp, one of the Apostolic Fathers who in turn knew the Apostle John, son of Zebedee. Before becoming bishop, Saint Irenaeus apparently studied in Rome where he was influenced by St. Justin Martyr. His major work, Against Heresies, which appeared around the year 185 AD, exposed the absurdities of the Gnostic cults of the day and included a strong presentation and defense of Catholic Christianity. It is the earliest compendium of Christian theology surviving from ancient times and is the first work that cites virtually every book of the Christian writings that we now call the New Testament. Saint Irenaeus is said to have won the crown of martyrdom around the year 200 AD. He is honored in the Roman liturgy on June 28.