In order to understand how Irenaeus viewed the efficacy of Scripture and the role Apostolic Succession plays, it is useful to understand how he organized his magnum opus Against Heresies.
In Against Heresies Book I, Irenaeus detailed a dozen or so Gnostic sects in order to show what the heretics taught. This showed that he understood his enemy. In Book II, he shows that the internal logic of Gnostic teachings often contradict one another, particularly focusing on the school of the Valentinians. In Book III, Irenaeus goes into detail about how the testimony of the Apostles, as preserved in the Scripture, is definitively opposed to Gnostic teachings.
Hence, it is from this context we must understand Irenaeus’ view of the Scripture and Apostolic Succession. Irenaeus (in his mind) has already shown that Gnostic teachings are self-contradictory. If that is not enough to convince someone not to be a Gnostic, he moves on to show that Gnostic teachings do not have a basis in real revelation (which is encapsulated by the teachings of Jesus Christ and His followers endowed by the Holy Spirit, the Apostles.) To the contrary, orthodox Christianity actually has a basis in God’s revelation, making it the true religion as opposed to Gnosticism.
In part I, we will cover how Irenaeus details the preceding ideas in the first two chapters of Against Heresies, Book III. Let’s begin:
We have learned from none others the plan of our salvation, than from those through whom the Gospel has come down to us, which they did at one time proclaim in public, and, at a later period, by the will of God, handed down to us in the Scriptures, to be the ground and pillar of our faith (AH 3.1.1).
Irenaeus in the above is intentionally ascribing to the Scriptures what 1 Tim 3:15 says of the Church. The reason he does this is in order to undercut Gnostic claims to authority, either by their claim to be the true Apostolic Church or to have better Scriptures. It is through this lens we must understand Irenaeus’ theory of the Church.
What Irenaeus means is that some Gnostics claim that the Apostles wrote the New Testament before achieving gnosis. THese Gnostics theorized that after achieving gnosis, the Apostles then bequeathed “better” Scriptures. Immediately, Irenaeus debunks this notion:
For, after our Lord rose from the dead, [the apostles] were invested with power from on high when the Holy Spirit came down [upon them], were filled from all [His gifts], and had perfect knowledge…(AH 3.1.1).
As we can see, the Apostles did not achieve some later gnosis, they were perfect when they indwelt by the Spirit. After making the above statement, Irenaeus details the different Gospels and letters the Apostles wrote, thereby carrying the implication these writings preserve the perfect teaching of the Gospel.
After noting that all of these Scriptures teach the rudimentary essentials of the Christian faith (one God, the Law and the Prophets i.e. Old Testament, etcetera–see AH 3.1.2) Irenaeus speaks of how Gnostics often try contradicting the authority of the Scriptures in order to shield their doctrines from scrutiny:
When, however, they are confuted from the Scriptures, they turn round and accuse these same Scriptures, as if they were not correct, nor of authority, and [assert] that they are ambiguous, and that the truth cannot be extracted from them by those who are ignorant of tradition. For [they allege] that the truth was not delivered by means of written documents, but vivâ voce [i.e. oral tradition] (AH 3.2.1).
It is with some irony that the Gnostics debase the Scriptures and their authority in a fashion markedly similar to certain major denominations today. In response to Irenaeus and the orthodox claim that the Scriptures act as a ground and pillar to faith, these men respond that Christians have:
1. The wrong Canon.
2. Their Scriptures are not vested with authority.
3. The Scriptures are too difficult to understand.
4. The Scriptures cannot be interpreted outside a knowledge of “apostolic tradition.”
5. There are essential Apostolic truths which were not passed down in Scripture but rather by oral tradition.
Irenaeus responds to the above ridiculous claims by invoking the doctrine of apostolic succession.
[W]hen we refer them to that tradition which originates from the apostles, [and] which is preserved by means of the succession of presbyters in the Churches, they object to tradition, saying…that the apostles intermingled the things of the law with the words of the Saviour…[T]hese men do now consent neither to Scripture nor to tradition (AH 3.2.2).
As we can see in Irenaeus’ invocation of the doctrine, and the Gnostic response to it, the purpose Apostolic Succession served was that it authenticated the orthodox Christian Scriptures. If we can see that a bishop of Smyrna (Polycarp), who was appointed by the Apostle John, had the same Canon and did not reject the perspicuity of the Scriptures, then we can reject the Gnostics’ claim to being Apostolic. This is why the Gnostics respond that even the Apostles as we know it from their historical writings had it wrong and that they are somehow more enlightened.
In Part II, we will cover in more detail what Irenaeus viewed Apostolic Succession to be.