Saint Irenaeus (born around 120/140 in Asia Minor, died around 200/203, probably in Lyon; Western feast day June 28; Eastern feast day August 23) was Bishop of Lugdunum (Lyon), an apologist, and one of the leading Christian theologians of the 2nd century. His work Adversus haereses (Against Heresies), written around 180, was a refutation of Gnosticism. Through his writings, Irenaeus contributed to the development of a canon of Scripture, the creed, and the authority of the episcopal office.
Early career
Although his exact date of birth is unknown, Irenaeus was born to Greek parents in Asia Minor. His own writings establish some biographical points, notably that as a child he heard and saw Saint Polycarp, the last known link to the Apostles, in Smyrna, before this elderly Christian was martyred in 155. Eusebius of Caesarea also mentions that after the persecutions in Gaul in 177, Irenaeus succeeded the martyr Pothinus as Bishop of Lugdunum. According to Eusebius, author of a fourth-century Church History, before becoming a bishop, Irenaeus had been a missionary in southern Gaul and a peacemaker among the churches of Asia Minor troubled by heresy.
The known biographical details, combined with his published works, are sufficient to paint a portrait of a remarkable life. Historical sources attest to a close cultural connection between Asia Minor and southern France (the Rhône Valley) in the 2nd century. According to tradition, Saint John the Apostle, very old and having “seen the Lord” (that is, Jesus), was living in Ephesus when Polycarp was young. Thus, three generations separated Jesus of Nazareth from Irenaeus in southern France.
Mediations and Tensions in the Church
The time of Irenaeus was marked by both expansion and internal tensions within the Church. In many instances, Irenaeus acted as a mediator between conflicting factions. The churches of Asia Minor still celebrated Easter on the same date (the 14th of Nisan) as the Jews celebrated Passover, while the Roman Catholic Church maintained that Easter should always be celebrated on a Sunday (the day of Christ's Resurrection). As mediator between the parties, Irenaeus declared that differences in external factors, such as the dates of festivals, should not be so serious as to destroy the unity of the Church.
Writings of Irenaeus: conflict with the Gnostics
However, Irenaeus adopted a completely negative and unreactive stance toward Marcion, a schismatic leader in Rome, and toward Gnosticism, a fashionable intellectual movement within the rapidly expanding Church that advocated dualism. Because Gnosticism was overcome by the early Church Fathers, including Saint Clement of Alexandria and Irenaeus, Gnostic writings were largely destroyed. In reconstructing Gnostic doctrines, modern scholars have therefore relied heavily on the writings of Irenaeus, who summarized Gnostic views before attacking them. After the discovery of the Gnostic library near Najʿ Ḥammādī (in Egypt) in the 1940s, respect for Irenaeus increased: he proved to be remarkably accurate in his reporting of the doctrines he rejected. All his known writings are devoted to the conflict with the Gnostics. His principal work consists of five books in a work entitled *Adversus haereses*. Originally written in Greek around 180, *Against Heresies* is now known in its entirety only in a Latin translation, the date of which is disputed (200 or 400?). A shorter work by Irenaeus, *The Manifestation of the Apostolic Preaching*, also written in Greek, survives only in an Armenian translation, probably intended for the instruction of young candidates for baptism. Irenaeus positively affirmed the validity of the Hebrew Bible (the Christian Old Testament), which the Gnostics denied, asserting that it upheld the laws of the wrathful creator God. Although Irenaeus does not explicitly refer to two testaments, an old and a new, he laid the groundwork for this terminology. He affirmed the validity of both testaments at a time when concern with the unity and difference between the two parts of the Bible was growing. Numerous works claiming scriptural authority, many of them by the Gnostics, flourished in the 2nd century. By attacking the Gnostics, Irenaeus helped to diminish the importance of these works and to establish a canon of Scripture.
Establishment of the Scriptures and the Creed
The development of the creed and the office of bishop can also be attributed to his conflicts with the Gnostics. Based solely on the New Testament, which concerns the salvation of humanity, one would not expect the creed to begin with an article on the creation of the world and humankind. However, because the Gnostics denied that the God revealed in the New Testament was the Creator, the first article of the creed was, for polemical reasons, directly linked to Genesis (“In the beginning, God created the heavens and the earth”). Irenaeus refers to the creed as a “Rule of Truth” used to combat heresy. The earliest lists of bishops were also countermeasures against the Gnostics, who claimed to possess a secret oral tradition directly from Jesus himself. Against such claims, Irenaeus argues that the bishops in various cities were known to the Apostles—and none of them were Gnostics—and that the bishops provided the only reliable guide for interpreting Scripture. With these lists of bishops, the later doctrine of the “apostolic succession” of bishops could be established. Even the unique position of authority of the Bishop of Rome is emphasized by Irenaeus, albeit in an obscure manner.
Although there is no evidence, other than legendary, concerning his death, the last decade of the 2nd century is generally considered to be the period of Irenaeus' death.
