When we list the most important theologians in the history of Christianity, many names quickly come to mind, including Jerome, Augustine, Anselm of Canterbury, Thomas Aquinas, Bonaventure, Robert Bellarmine. Each of these figures has been rightly declared to be Doctors of the Church (doctor being Latin for “teacher”), a group that includes a total of 36 saints (32 men and 4 women), who were among the greatest teachers in the history of the Catholic Church.

There is a saint who has been left off that list, and his omission is something that many Catholics are seeking to correct. Countless believers through the centuries have petitioned the Vatican to name him as one of the Doctors of the Church—including the US bishops during their November 2019 general assembly. His work has influenced the thought and teachings of many popes. The man I speak of is St. Irenaeus of Lyons.

Born in the second century (ca. 130 AD), Irenaeus was different from many of his contemporaries in that he was raised in the faith, not a convert. He was taught and ordained by St. Polycarp, who had been taught by St. John the Apostle himself. Irenaeus would rise to eventually become the bishop of Lyons (a see that exists to this day). There are few sources that provide biographical details of his life, but the tradition holds that he was martyred in the beginning of the third century.

The greatest threat to the Church during Irenaeus’s life (apart from Roman persecution) was the heresy of Gnosticism. As the saying goes, murder kills the body, but heresy kills the soul. In short, Gnosticism was a belief that a select few had received “secret knowledge” regarding the teachings of Jesus. Gnosticism came in a wide variety of forms in its time, many of which denied the humanity of Jesus, suggesting he was a spirit who only appeared to have a body, thus denying the Crucifixion and Resurrection. Some claimed that there were competing gods of the Old and New Testaments. Many Gnostics vehemently despised this world, seeing it as corrupted by evil, advocating for anti-natalism (thinking childbirth would perpetuate an evil world), and earned a condemnation from St. Paul (cf. 1 Timothy 4:3).

Enter Irenaeus, who challenge these ideas with his magnum opus Against Heresies. In this work, the saint identified and critiqued the doctrines of Gnosticism (particularly Valentinianism). He challenged claims that Gnostic “sources” could be trusted, through appeals to sacred Tradition. Pointing to the bishops, he demonstrated how they exercised their authority throughout the world. He explained how the Apostles had instituted bishops in their own time, and that many of their successors, including himself, still living at that time. He wrote:

“For or if the apostles had known hidden mysteries, which they were in the habit of imparting to the perfect apart and privily from the rest, they would have delivered them especially to those to whom they were also committing the Churches themselves” (Book III, Chapter 3).

In the same work, Irenaeus also emphasized the importance of the Roman see, writing:

“That tradition derived from the apostles, of the very great, the very ancient, and universally known Church founded and organized at Rome by the two most glorious apostles, Peter and Paul; as also (by pointing out) the faith preached to men, which comes down to our time by means of the successions of the bishops. For it is a matter of necessity that every Church should agree with this Church, on account of its preeminent authority.”

Immediately following this passage, Irenaeus enumerated the list of bishops who succeeded St. Peter in Rome, from St. Linus through his contemporary, St. Eleutherius.

Here we discover that not only was Irenaeus a gifted theologian capable of addressing the heresies of the Gnostics, but he also disproves the anti-Catholic myth that the Church is an apostate political product of the Dark Ages. Irenaeus has been extremely influential to the field of apologetics (this is where I first encountered him). His work confirms not only an early list of the immediate successors of St. Peter, but he also demonstrates that the early Church very much believed in Baptismal regeneration and the Real Presence of Our Lord in the Eucharist.

But Irenaeus’s importance goes far beyond the Catholic/Protestant debate regarding the true Church. Referencing the classic philosophical arguments for an eternal creator who has no needs, Irenaeus invoked this as a paradoxical proof to demonstrate that God’s love is gratuitous and free. Because God does not need us, this is a sign of his love for us. His most famous quote demonstrates the beauty of creation: “The glory of God is a living man,” because we can comprehend the goodness of God. Going further, he writes “if the manifestation of God which is made by means of the creation, affords life to all living in the earth, much more does that revelation of the Father which comes through the Word, give life to those who see God.”

I hope that the recent groundswell of support for St. Irenaeus will result in a newfound appreciation for this great saint and teacher. I pray that eventually, Pope Francis (or one of his immediate successors) will declare him a Doctor of the Church. St. Irenaeus was truly one of the greats, and his work will continue to influence the Church until Our Lord comes again.

Image: Stained glass image of Irenaeus of Lyon, by Lucien Bégule / Photo by Gérald Gambier. Public Domain https://commons.wikimedia.org/w/index.php?curid=10565837

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Raised in Connecticut, Kevin has spent the last five years living in the Boston area. During his education at Xavier High School in Middletown, CT by the Xaverian Brothers, Kevin took an interest to theology, ranging from simple apologetics to existential literature. He is a passionate cinephile and baseball fan, anxiously awaiting the return to movie theaters and baseball stadiums, above all: Fenway Park, which is his Heaven on Earth.

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