Today is the Memorial of Saint Irenaeus.
Irenaeus was born in the 2nd Century AD in Smyrna, Asia Minor (current day Izmir, Turkey). He was reared in a Christian family, and became a student of St. Polycarp, who himself had been a disciple of the Apostle John.
Eventually, Irenaeus was ordained into the priesthood, and served as a priest in Lugdunum, Gaul (now Lyon, France). He eventually became the bishop of that city.
Irenaeus wrote many books explaining the Catholic Faith, while also defending it against heresy. He especially went to war against the errant philosophy of Gnosticism. Gnosticism held that the material world had been created by an evil god, and that men must seek to escape the material world by obtaining a certain secret knowledge (that only the Gnostics had). Irenaeus showed, in his preaching and writings, how much the ideas of Gnosticism contradicted the teaching of Scripture.
Scripture states that there is only one God; and He is a good God. This good God created all things visible and invisible, material and immaterial, and both the body and the soul. However, due to man’s disobedience, sin entered human nature and has severely affected it. The eternal Christ, in the 1st Century AD, took on flesh and became a man (a true physical man), Jesus of Nazareth. He did this to redeem and renew all things, material and immaterial.
Irenaeus claimed that his Apostolic connection (he was a disciple of Polycarp, and Polycarp was a disciple of the Apostle John, and the Apostle John was a disciple of Jesus) gave him authority over the Gnostics. Since he could trace the authority of his message directly back to Christ, his teaching on the Faith was valid while the teaching of the Gnostics was heretical.
Irenaeus taught that the Catholic bishops of the cities of the Roman Empire could easily be traced in succession from the Apostles, and, therefore, provided the only correct interpretation of Scripture (i.e., Tradition). His writings also testify to the Catholic view of the Eucharist, the primacy of the Roman Church; and provide the earliest (2nd Century AD) mention that all four gospels—Matthew, Mark, Luke, and John—were viewed by the Church as canonical Scripture.
Irenaeus was buried under the Church of St. John (later became the Church of St. Irenaeus) in Lyon. Unfortunately, his tomb and remains were destroyed by the Huguenots in the 16th Century.
Christo et Ecclesiae,