All of the major religions have some sort of factionalism. Within Buddhism, you have Theravada, Mahayana, Zen, Pure Land; within Islam, there are Sunni and Shia; within Judaism, Orthodox, Conservative, Reform. Is early Christianity any different?
In fact, the divisions within early Christianity are completely different not only from those within these other religions, but even from the divisions in later Christianity after the Council of Nicaea. The controversy between James, Peter, and Paul in the early church (Galatians 2, Romans 14, I Corinthians 8-10) split “Jewish Christianity” from the rest of the church. According to Acts 15, it was a dispute over Jewish rituals; but the Ebionites understood it as a controversy over meat consumption and meat sacrificed to idols. We can understand this question better by comparing the controversies in Buddhism and Islam with those in early Christianity.
In the case of Buddhism and Islam, you have a dispute between just a handful of groups, or even just two groups. The dispute is well-ordered; all sides share a clear core of teachings, but split over other more controversial teachings or practices. The disputes often come down to questions of detailed and subtle interpretation. For example, the issue of vegetarianism between Theravada and Mahayana revolves around the Buddha’s (alleged) instruction to his monks that they may eat meat if they do not suspect that the animal was killed specifically for them.
But this occurs against a background of a shared core of teachings. In the case of Buddhism, for example, you have the four noble truths and the five precepts (against killing, lying, stealing, sexual immorality, and intoxicants). All the various groups accept these and seek enlightenment and release from suffering, though with varying interpretations. In the case of Islam, you have the entire Qur’an, which is accepted by all Moslems. The Sunni-Shia split is more over questions of authority with some rituals and prayers being observed differently, leaving the ethical and theological core of the religion broadly similar.
What is striking about early Christianity is its absolutely baffling nature, which is evident not just to us, but to the participants themselves. You can’t read the history of the early church without being aware of this. Instead of a few established groups taking rhetorical potshots at each other across well-defined borders, you have a melee of dozens of different groups with ill-defined borders.
Much of the early Christian work in The Ante-Nicene Fathers is just polemic against heretics. Origen remarks that “many” Christians have disputes with each other on “subjects of the highest importance.” Ireneaus spills a lot of ink describing and denouncing myriad groups in early Christianity; Hippolytus chips in with his own lengthy treatise. Epiphanius counts 80 different heretical groups; but Theodoret counts only 60. Tertullian describes heresy as widespread, spends a lot of time denouncing it, but eventually finds himself outcast as a heretic.
In fact, in the first two Christian centuries you have no coherent body of shared beliefs at all. You can find myriad views of God, Jesus, the Bible, and ethics; even monotheism itself is disputed. It isn’t until the council of Nicaea in the fourth century that a coherent “core” of the religion emerges. Even then this core has numerous factors (the virgin birth and the divinity of Jesus, for example) which are fundamental to the religion but which can’t really be traced back to the first few decades of Christianity, despite centuries of rhetorical efforts.
Why did this happen? It’s basically because the core of the primitive religion was found only in the Jerusalem church — James and his successors. Paul was not a peer of the Jerusalem church. He never knew the earthly Jesus, and when the split occurred, James took the rest of the family of Jesus, the Jerusalem church, and essentially everyone who either knew Jesus or was living in Palestine at the time with him. “Even Barnabas was carried away,” reports Paul in Galatians.
So what happened when, several decades after the division between Paul and Jewish Christianity, the Jerusalem church was left behind in the wake of the devastating defeat of the Jewish revolt against Rome? To begin with, gentile Christianity was ascendant, but there was a more important effect: the entire Christian religion, cut off from its source, had to be interpreted second-hand.
Neither Paul nor Jesus really had a hand in the shape this later religion took. You can see this by looking at what Paul and Jewish Christianity agreed on. Both Paul and the Jewish Christians rejected the Old Testament (e. g. Homilies 2.38, Romans 7:6) and held to the spiritual, not physical, resurrection (e. g. Recognitions 3.30, I Corinthians 15:42, 50); they agreed on nonviolence between humans, at least (e. g. Recognitions 3.42, Romans 12:14); and they agreed on the need for simple living and rejection of wealth (e. g. Panarion 30.17.2, Romans 12:2, 16). Yet Christianity just a few centuries later had rejected all of these, except for a token allegiance to helping the poor. From there it is a straight line to a convoluted theology, preaching violence against unbelievers, and amassing wealth.
To make Christianity comparable to Islam, you would have to imagine that Jesus wrote or dictated the entire New Testament. To make Christianity comparable to Buddhism, you’d have to imagine that Jesus at least wrote or dictated the Nicene Creed and perhaps founded a few monasteries. But Jesus did none of this. All he left were his Jewish followers and the Jerusalem church.
Working in the other direction, to make Buddhism comparable to Christianity, you’d have to imagine dozens of different groups some having 3, some 4, some 18 noble truths, with some groups denying that the goal was enlightenment and others denying that life was suffering. To make Islam comparable to Christianity, you’d have to imagine that there were, a century after Mohammed, dozens of different versions of the Qur’an, all claiming to be from Mohammed.
When the gentile church rejected Jewish Christianity, it essentially was starting over. The results of this controversy was not that Christianity was split into two or three factions; it was shattered into countless factions. That’s what makes the history of Christianity different from the history of other religions. Neither Christians nor scholars have acknowledged the reality of these divisions. A religion that does not know where it came from, does not understand where it is going, either; and that is exactly the dilemma of modern Christianity.