Despite all the buzz about diversity in early Christianity, we have no reason to doubt that the mainstream church during this time period was still one that could be generally identified as “orthodox.”
I’ve noticed that Michael Bird has recently posted an article on heresy and orthodoxy in early Christianity. From what I can tell (I can’t see the entire article because it’s behind the paywall), he is pushing back against the popular narrative, originally suggested by Walter Bauer in his 1934 book Orthodoxy and Heresy in Earliest Christianity, which insists that Christianity was wildly diverse in the earliest centuries and that the heretics outnumbered the orthodox. It was not until the 3rd and 4th centuries, according to Bauer, that the orthodox began to turn the tide.
But I think there’s an additional way to test Bauer’s theory. Let’s ask a simple question: who were the bishops in second-century Christianity? If heresy was as widespread as orthodoxy, we should expect to find a number of bishops that are openly Marcionite, Ebionite, Gnostic, and beyond.
The problem for Bauer’s thesis is that this is precisely what we don’t find.
When we examine bishops from the second century we find a litany that fit nicely within the orthodox camp: Ignatius, Polycarp, Clement of Rome, Papias, Hegesippus, Irenaeus, Theophilus of Antioch, Anecitus of Rome, Polycrates of Ephesus, Victor of Rome, Demetrius of Alexandria, Melito of Sardis, Theophilus of Caesarea, and Dionysius of Corinth.
While these leaders certainly did not agree on everything, it is evident from their writings, or from historical reports about them, that there are no reasons to identify them with heterodox groups like the Marcionites, Gnostics, or Ebionites.
What is particularly noteworthy about the above list is that they represent a wide geographical range: Lyons (Gaul), Smyrna, Antioch, Hierapolis, Rome, Sardis, Ephesus, and Corinth. In other words, these orthodox leaders were not cordoned off into some small outpost of early Christianity.