Christianity was shattered into many different factions at an unusually early stage. Bitter disputes are recorded in Paul’s letters between Paul and Peter and James. You can’t read the collection The Ante-Nicene Fathers without seeing that much of early Christian literature is polemical. It is directed, not against external enemies, but against other followers of Jesus who are “misrepresenting” Christianity.

Irenaeus, Hippolytus, Tertullian, Epiphanius, and Theodoret wrote lengthy refutations of their Christian opponents. Origen ruefully comments that “many” Christians have differences of opinion on “subjects of the highest importance.” This is totally unlike what we see in Buddhism, Islam, or even modern Christianity, where all the various schools of thought resemble each other in broad outline. In early Christian writings, we sometimes see Christian polemics against Jews or pagans; but it is not nearly as voluminous as the polemics against other Christians.

What do scholars make of the huge multiplicity of different Christian groups? For example, what caused it? Any ideas, scholars? Or anyone else?

For me, this is a central historical problem in understanding early Christianity. The vast extent of early Christian factionalism shifts our attention to the question, what caused this? Most likely, it is because the authority of the Jerusalem church was destroyed at an early stage. After the destruction of the temple in 70 CE, there was only a greatly weakened Jerusalem church, unable to provide direction to the many diverse gentile churches with which it had already experienced some considerable friction. The natural result was factionalism.

This is an important historical issue because it shifts our attention directly to the conflicts in the early church. It also suggests that there was no smooth transition from the Jewish followers of Jesus to gentile Christianity.

Yet, with a few exceptions, Jesus scholars are often dismissive of this question. I mentioned the problem of early Christian factionalism to an Iliff professor whom I met to talk about the Ebionites. She brushed it off, saying that all religions experience factionalism. Well, yes, these other religious movements do experience divisions, but the conflicts in early Christianity are utterly unlike the factionalism one sees in other religious movements. Bart Ehrman, to his credit, acknowledges factionalism, his “lost Christianities,” but in my view doesn’t really account for it.

Standard pious Christian histories, most scholars, and most Christians are committed to an “incrementalist” view of early Christian history. First there was Jesus, then he had disciples, then each generation of followers added new layers to the original tradition. They would sometimes amplify this or that point, sometimes add completely new material, sometimes cover something else up. If we can just peel back the later layers, voilà: we have the historical Jesus.

Factionalism in the early church renders this view implausible. An incrementalist theory of Christianity would imply that we would have just a handful of different groups, all of which agree in broad outline with each other, differing with each other only on one or two key issues, or on questions of religious authority, or sometimes even just on vague questions of detail that baffle outsiders. New emerging factions would need to compete with the central authority, and many of them would be squelched before they were started. Those that succeeded would resemble on many substantial points the religion from which they were breaking away.

In fact, this is just what you see in Buddhism, Islam, modern religious movements, and even Christianity itself after the Council of Nicaea. Think of the divisions of Buddhism into Theravada, Vajrayana, and Mahayana; the Sunni-Shiite division in Islam; or Eastern Orthodox, Roman Catholic, and Protestant Christianity. All of the divisions of these various religious movements agree with their co-religionists on most issues, and it is often difficult for outsiders to understand what really separates Sunni from Shiite, for example.

But this is not what you see in early Christianity. Early Christian literature is preoccupied with polemics, not against other religions (Jews or pagans, for example), but against other Christians, deemed to be “heretics.” There are countless groups: Theodoret counts 60 different heretical groups, but Epiphanius counts 80. There are “gnostic” groups and Jewish Christian groups. Irenaeus, Tertullian, Hippolytus, and others weigh in with their own massive works. Origen remarks that heresy is widespread, and that Christians disagree with each other not just on incidental questions, but on questions of the highest import. They cannot agree on anything except that they like Jesus; even monotheism itself is in question.

There is a much better explanation for early Christian factionalism — that the incrementalist view of early Christian history is wrong. There was a crisis and discontinuity in the early church, with its epicenter around the year 70, which disconnected the later church from the earlier church. As a result, the Christian religion was propagated in the gentile world without any central authority to smooth out ideas and practices. It had to be reconstituted using whatever materials survived and were politically viable.

The Jerusalem church should have been that authority. But it was caught up in a huge dispute with its chief missionary, Paul, just a few decades after Jesus left the earth, creating a split between the gentile churches to whom Paul preached and the Jerusalem church. Then, scarcely more than a decade later, the great Jewish revolt against Rome intervened. It was devastating to Jewish Christianity, just because the destruction and loss of life affected everyone in the region; but gentile Christianity was scarcely affected at all.

The result? There is no central authority for the early church after the year 70. Jewish Christianity, greatly weakened, is unable to exert any meaningful leadership. Each of the various gentile churches is an authority unto itself, and it takes centuries to sort out the new religion, even as it expands throughout the Roman Empire. Within a few decades of the destruction of the Jerusalem temple, gentile Christianity faces a spiritual civil war, with the church in a life and death struggle with gnosticism. A century later, Jewish Christianity is condemned as a heresy, and not even a particularly important heresy; the Jewish Christian Ebionites rate just a few sentences in Irenaeus’ massive work Against Heresies.

In the beginning, Jesus and his first disciples were entirely Jewish; and for decades there is no obvious split between Judaism and Christianity. But in the end, Jewish Christianity is condemned as a heresy. Neither Christian thinkers nor scholars have a good explanation for this fact. If we postulate that the authority of this early church was disrupted by a series of crises culminating in the devastation of the Jewish revolt against Rome and the destruction of Jerusalem in the year 70, then the puzzling aspects of Christian factionalism make sense.