Irenaeus and Christian Orthodoxy


Bradley Nassif

Article ID:



Jan 16, 2024


Feb 21, 2022

This article first appeared in the Christian Research Journal, volume 43, number 1 (2020). For further information or to subscribe to the Christian Research Journal please click here.

The famous New Testament scholar, N. T. Wright, was recently asked, “Who is the most relevant theologian for the 21st century?” Without hesitation, Wright replied, “Irenaeus.” The reasons for that choice are not surprising when one considers the lasting significance of Irenaeus’s work. Irenaeus is the star witness of the church in the late second century. He is important for many reasons, but especially for his defense of Christian orthodoxy against the false teachings of the popular Gnostic movement of his day. His arguments are a witness to the unity and continuity of apostolic tradition that has been handed down in the church’s Scripture, creed, and clergy.


Little is known of Irenaeus’s life (c. 130–202). The historian Eusebius of Caesarea (c. 300) tells us that Irenaeus was one of the last Christian writers to have learned the faith from Polycarp (died c. 155),1 a bishop of Smyrna where Irenaeus himself was possibly born (modern Izmir in Turkey). Polycarp is important because he links Irenaeus to the apostolic age. Polycarp claimed he had personally known the apostle John and was appointed as bishop of Smyrna by some of the original apostles.2 Irenaeus, therefore, claimed that his faith was a continuation of what was handed down by Polycarp and other disciples of the apostles. Around 177, Irenaeus moved from Smyrna to southern Gaul where he became a bishop of the church of Lugdunum (modern Lyons in France). Only two of his works survive: The Demonstration of the Apostolic Preaching and Refutation and Overthrow of Knowledge Falsely So-Called, more commonly known as Against Heresies, which consists of five books that describe Irenaeus’s response to various forms of Gnosticism.


“Gnostic” comes from the Greek word gnosis, meaning knowledge. Gnosticism was a loosely organized and variable system of belief that emphasized salvation comes by possessing secret spiritual knowledge. The movement is hard to define because there were more than 200 varieties in the ancient world, some closely related to Christianity. The origins are debated, but Gnosticism seems to have been a blend of Zoroastrianism, apocalyptic Judaism, and perhaps Christianity. Incipient Gnosticism is manifested in several New Testament documents and becomes more developed around Irenaeus’s time. Some of its most influential leaders were Valentinus in Rome, Basilides in Egypt, and Marcion in Asia Minor. Marcion was nearest to being a Christian. He essentially created his own Bible by rejecting the Old Testament and accepting only Luke and an edited version of Paul’s letters. This obviously posed a serious challenge to the church regarding the question of which books should be included in the biblical canon. Irenaeus tells us that Marcion “dismembered the Epistles of Paul, removing all that is said by the apostle respecting that God who made the world, to the effect that He is the Father of our Lord Jesus Christ, and also those passages from the prophetical writings which the apostle quotes, in order to teach us that they announced beforehand the coming of the Lord.”3

Gnostic teachings were marked by a dualistic belief that the physical world and all that is in it are corrupt, and only the spiritual realm that is uncontaminated by matter is good. These beliefs had several consequences for the Gnostic understanding of creation, ethics, Christ, and salvation. First, if the High God (pure spirit) is good, then he could not have created the world. Only a lower god, called the Demiurge, created matter. The Demiurge came from a long line of degenerate divine beings (known as the Divine Fullness), which descended from the High God. The Demiurge was the creator God of the Old Testament. Since he created a material human body, it is evil. Some Gnostics, therefore, lived very ascetic lives by avoiding bodily pleasures, while others were indifferent to matter and indulged the body by living gluttonous, immoral lives.

The Jesus of Gnosticism is not the Jesus of the Bible’s four gospels. In Gnosticism, Christ was merely one of many spiritual messengers who came into the world to bring enlightenment. Christ only appeared to be human, since God would not have dirtied his hands by becoming one of us. The Jesus of Gnosticism ends up being a teacher of Gnostic secrets, not the incarnate God who died on the cross for our sins and bodily rose from the dead for our salvation. Salvation for the Gnostics consisted of the illuminated human spirit’s escape from the prison of the body and could be acquired only by possessing secret knowledge from progressive revelations. This elite knowledge was passed down from person to person as an intellectual faith that put Gnostics above the spiritually dull, ordinary people who were unable to grasp such lofty teachings.


Two major issues were at stake in the Gnostic challenge: What is the true faith, and how has it been passed on from the apostles to the churches they left behind? Irenaeus refutes false Gnostic doctrines by appealing to three criteria: the orthodox church’s apostolic canon, creed, and clergy.

Apostolic Canon. True faith, according to Irenaeus, is found in the church’s four gospels of Matthew, Mark, Luke, and John, not the Gnostic gospels.4 “But those who are from Valentinus…put forth their own compositions [and] boast that they possess more Gospels than there really are,” writes Irenaeus. “For if what they have published is the Gospel of Truth,5 and yet is totally unlike those which have been handed down to us from the apostles, any who please may learn, as is shown from the Scriptures themselves, that that which has been handed down from the apostles can no longer be reckoned the Gospel of Truth.”6

The Gnostics had the wrong Jesus because they had the wrong Bible. The Christ of Gnosticism was not the Christ who was revealed in the apostolic Scriptures.

Apostolic Creed. The expression “rule of faith” (Latin: regula fidei) or “canon of truth” (Greek: kanon pisteos) appears in Irenaeus’s writings as a source and norm of Christian faith. The “rule” is simply a brief, flexible summary of the apostolic faith that was passed down orally or in writing and associated with baptism. It provided a hermeneutical standard for the proper interpretation of the Christian faith. The “rule” contradicts the heretical Gnostics on crucial points of difference, which I noted earlier. It was also not an exhaustive statement of the Christian faith in areas such as baptism, the Eucharist, and other commonly held doctrines. Irenaeus tells us that the heretics were very clever in the way they manipulated and distorted Scripture, but they would not have misled anyone who “retains unchangeable in his heart the rule of the truth which he received by means of baptism.”7 Here is Irenaeus’s classic description of the church’s theological unity (the added bold emphasis highlights the doctrines):

The church, though dispersed throughout the whole world, even to the ends of the earth, has received from the apostles and their disciples this faith: She believes in one God, the Father Almighty, Maker of heaven, and earth…and in one Christ Jesus, the Son of God, who became incarnate for our salvation; and in the Holy Spirit…and the birth from a virgin, and the passion, and the resurrection from the dead, and the ascension into heaven in the flesh of the beloved Christ Jesus, our Lord, and His [future] manifestation from heaven in the glory of the Father to gather all things in one, and to raise up anew all flesh of the whole human race.8

This identical faith was not secretly passed down from person to person, as in Gnosticism. Rather, it was preserved and visible in all the apostolic communities throughout the world:

As I have already observed, the Church, having received this preaching and this faith, although scattered throughout the whole world, yet, as if occupying but one house, carefully preserves it. She also believes these points [of doctrine] just as if she had but one soul, and one and the same heart, and she proclaims them, and teaches them, and hands them down, with perfect harmony, as if she possessed only one mouth. For, although the languages of the world are dissimilar, yet the import of the tradition is one and the same. For the Churches which have been planted in Germany do not believe or hand down anything different, nor do those in Spain, nor those in Gaul, nor those in the East, nor those in Egypt, nor those in Libya, nor those which have been established in the central regions of the world.9

Notice that Irenaeus does not say that the church or its bishops can decide what the content of the tradition is. Neither does he claim that God has granted ongoing revelation to the community so that new truths may be added or replace the original apostolic deposit. Nor does he say that one apostolic church, such as Rome or any other, has a corner on the truth and all others must submit to its authority. Rather, the tradition is held equally and identically in all the apostolic churches, whether they be in Germany, Spain, Egypt, or elsewhere.

Apostolic Clergy. A third criterion for discerning Christian orthodoxy is Irenaeus’s doctrine of apostolic succession — an appeal to the uninterrupted transmission of truth entrusted to church leaders whose ordinations could be traced back to Christ’s apostles and their successors. This historical preservation of truth occurs within local churches and functions as a public witness against the errors of the Gnostic religion:

It is within the power of all, therefore, in every Church, who may wish to see the truth, to contemplate clearly the tradition of the apostles manifested throughout the whole world; and we are in a position to reckon up those who were by the apostles instituted bishops in the Churches, and [to demonstrate] the succession of these men to our own times; those who neither taught nor knew of anything like what these [heretics] rave about. For 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.10 (Emphasis in original.)

Although Roman Catholics, Eastern Orthodox, conservative Anglicans, and others believe that apostolic succession is vital to the preservation of truth, most Protestants do not. The Reformers believed there was no need for apostolic successors because there were no bishops in the apostolic age, and the teachings of the apostles in the New Testament were sufficient to combat heresy.


What is the true faith, and how has it been passed on from the apostles to the Christians they left behind? It would be difficult to overstate the importance of Irenaeus’s answers to these questions. Aside from the New Testament, he was the first theologian in history to provide the criteria by which believers may discern orthodoxy from heresy. By stressing the role of apostolic Scripture, the “rule of faith,” and the continuing presence of faithful ministers, Irenaeus emphasized the historical continuity of the church as the ongoing locus of apostolic tradition. The church’s Bible (not the Gnostics’ Bible) is the supreme authority, but it can be rightly understood only within the context of the “rule of faith” and the church’s apostolic succession of ministers as attesting witnesses to its truth.

Irenaeus is also a contemporary theological figure for recognizing authentic Christian identity today. Like the counterfeit Christ of Gnosticism, the Christ of modern liberal theology offers a cheap imitation of the real Jesus. Faithful churches are growing today while liberal ones are losing membership by the droves. Why? Because the liberal Jesus is a Jesus who is powerless to overcome the fallen condition of our humanity. He is incapable of defeating the world, the flesh, and the devil. The Christ of liberalism is a good teacher who was not the incarnate God born from a virgin, did not forgive the sins of the world by his sacrificial death on the cross, did not conquer death, and did not usher in the new creation through a bodily resurrection and glorious second coming.

In many ways, Irenaeus’s relevance is perhaps greater now than it was in the second century because of the widespread presence of these and other false doctrines that survive in churches and educational institutions worldwide today. By relying on the church’s canon, creed, and faithful clergy, Irenaeus offers an antidote to the interpretive anarchy of an individualistic approach to Christianity. He reminds us that our interpretation of the Christian faith is not to be an exclusively private matter reserved for intellectual elites; rather, it is a communal witness to “the faith that was once for all entrusted to God’s holy people” (Jude 3 NIV).

Bradley Nassif, PhD, is Professor of Biblical and Theological Studies at North Park University.


  1. Eusebius, Ecclesiastical History 20.
  2. Eusebius, Ecclesiastical History 20.6; Tertullian, Prescription Against Heretics 32.
  3. Irenaeus, Against Heresies, Book 1.27.2, in The Ante-Nicene Fathers, vol. 1, trans. Alexander Roberts and William Rambaut, ed. Alexander Roberts, James Donaldson, and A. Cleveland Coxe (Buffalo, NY: Christian Literature Publishing Co., 1885), rev. Kevin Knight, New Advent,
  4. Irenaeus, Against Heresies 1. This is the first historical witness to the collective authority of our four canonical gospels.
  5. The Gospel of Truth is a second-century Gnostic gospel.
  6. Irenaeus, Against Heresies 11.9, in The Ante-Nicene Fathers, vol. 1,
  7. Irenaeus, Against Heresies 9.4, in The Ante-Nicene Fathers, vol. 1,
  8. Irenaeus, Against Heresies 10.1, in The Ante-Nicene Fathers, vol. 1,
  9. Irenaeus, Against Heresies, 10.2, in The Ante-Nicene Fathers, vol. 1,
  10. Irenaeus, Against Heresies 3.1, in The Ante-Nicene Fathers, vol. 1,


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