St. Irenaeus
One
St. Irenaeus was born around 130 AD in Smyrna (modern-day İzmir, Turkey)
He was a disciple of Polycarp, the Bishop of Smyrna, who himself was a direct disciple of John the Apostle. Think about that, Irenaeus was taught by someone who got everything straight from the Apostles. Irenaeus learned the Catholic faith from someone who learned Catholicism directly from the Apostles. The whole mission of Irenaeus was simply to hand on faithfully what the Apostles taught.
At some point, Irenaeus moved to Ludgum Gaul, what we now know as Lyon, France. During the persecution of Marcus Aurelius, Irenaeus was a priest of the Church of Lyons. The clergy of that city, many of whom were suffering imprisonment for the Faith, sent him (177 or 178) to Rome with a letter to Pope Eleutherius concerning Montanism. While he was in Rome, 42 Catholics, including Bishop Pothinus were tortured and put to death for their faith. When Irenaeus returned he was appointed bishop of Lyon.
He was a great bishop of the Catholic Church as well as a great theologian. He wrote two books that can really be considered early catechisms. The first book is the Demonstration of the Apostolic Preaching and the second was called Against Heresies.
St. Irenaeus was martyred around the year 200.
Two
The Pope and Bishops
Many people mistakenly think Jesus sent out his disciples without any thought of structure. Then hundreds of years later this whole Catholic Church thing sprung up, then they made a Pope and bishops, a hierarchy, and all the rules. Well, Irenaeus is a pretty good witness to what Jesus really set up and did. Recall that Jesus taught John, then John taught Polycarp, and Polycarp taught Irenaeus. Then Irenaeus wrote it all down in two books.
In those books, Irenaeus teaches that Jesus established Peter as the first Pope and the Apostles as the first bishops and their successors teach with the authority of Christ. He teaches that Mary has a very important role in Christianity, and that the Eucharist is the real presence of Jesus, body, blood, soul, and divinity.
Let’s take the first one. Jesus set up Peter to be the first Pope and the Apostles as the first Bishops. Jesus gave them his own authority to teach in his place when he said to them, “He who hears you hears me, and he who rejects you rejects me.”
The Pope and the Catholic Bishops are the successors of the Apostles. They teach with the authority of Jesus handed down by Peter and the Apostles. That means that if we reject the official teaching of the Catholic Church, we are rejecting Jesus. St Irenaeus writes, “In order that the full and living Gospel might always be preserved in the Church the apostles left bishops as their successors. They gave them their own position of teaching authority.”
Three
Mary
What makes Mary so important to us?
Irenaeus probably the most fundamental answer to that question, and the answer the Church gave in the very beginnings of Christianity, is that Mary is our New Eve.
Scripture is very clear that we humans originally got into this mess of sin and suffering because of a man named Adam. Scripture is also very clear that we get out of this mess only through the New Adam, Jesus Christ. But of course, there wasn’t just an original Adam who led humanity to death. There was an original Eve. And there isn’t just a new Adam who brings us to life, there’s a New Eve.
Look at the parallels between Mary and Eve. A fallen angel comes to the first eve and says, “If you want, you can make man to be like God.” The angel Gabriel comes to the New Eve and says, “If you want, you can make God to be like man.” The first Eve says yes to the bad angel, and she gives the forbidden fruit, the instrument of damnation, to the first Adam. The New Eve says yes to the good angel, and she gives human flesh, the instrument of salvation, to the New Adam. If Adam and Eve are both in some way responsible for our fall, then Jesus and Mary, the New Adam and the New Eve are together responsible for our salvation.
St. Iraneaus calls Mary “the cause of salvation for herself and for the whole human race.” He said that, “The knot of Eve’s disobedience was untied by Mary’s obedience,” and that “As the human race was bound to death because of a virgin, so it was set free from death by a Virgin.”
Four
The Eucharist
Once again, remember that Irenaeus was taught by Polycarp who was taught by John the Apostle. And Irenaeus believed his mission was to simply hand on what the Apostles taught.
So, then, did Irenaeus say anything about the Eucharist? Absolutely! Already, around the year 180 Irenaeus taught what the Church teaches today: that in the most blessed sacrament of the Eucharist the body and blood, together with the soul and divinity of our Lord Jesus Christ and, therefore, the whole Christ is truly, really, and substantially contained.
In his book Against Heresies (Book III, Chapter 22) Irenaeus writes, "We must not listen to those who say that there is no flesh and blood in the Eucharist, and that flesh and blood belong to a corrupt and mortal creation. But we believe that the flesh and blood of Christ are truly present, and that He Himself has given His flesh and blood in the Eucharist."
Five
The Glory of God is man fully alive
One of my favorite lines from Irenaeus is this, “The glory of God is man fully alive.” What does this mean?
At your Baptism, the Trinity, Father, Son, and Holy Spirit came to dwell in your soul. By their presence within you, you participate in their divine nature as adopted sons and daughters of God. And by sharing in their divine being you can share in their divine activity. Most especially to love the way God loves.
We call this Divinization. We don’t become God on our own. But by union with Jesus, we participate in his divine being and his divine activity. Jesus gives us three things to make this happen: The Catholic Church, Mary as our Mother, and the Eucharist.
Irenaeus summed it up when he wrote, “For this is why the Word became man, and the Son of God became the Son of man; so that man, by entering into communion with the Word and thus receiving divine sonship, might become a son of God.” Against Heresies 3, 19