Nowadays Christianity has several sects: Catholicism, Eastern Orthodox, Coptic, and Protestantism is broken into about a bajillion different sects, usually divided into those who believe in the Trinity (Lutherans, Episcopalians) and those who don't (Pentecostals, Jehovah's Witnesses). But even when I see the violence between these groups, to me they're more or less the same thing just with lightly different flavors. Why? Because I've studied early Christianity and I knew how freaky that shit could get before it was institutionalized.
In the early 300s Emperor Constantine assumed power over the Roman Empire and within a few decades turned Christianity from the reviled religion into one that was legally accepted and on the path to dominance. Divided peoples can unite when faced with a common enemy. America experienced it after the events of September 11th. But once Constantine removed Christianity's — the Roman state throwing their members to the lions — the variant beliefs suddenly came to the surface. They were always there, it's just most people were focusing on hiding and not dying to really care whether their neighbors were practicing the same blend of Christianity. Now that there was no distraction, what was ignored for over a century suddenly was in everyone's face. Constantine quickly realized the leaders of his favored religion were squabbling with one another and called a council to Nicaea in 325 to get everyone to agree and standardize the religion. He had mixed results, but it was the first step in creating the Christianity we know today by literally killing all the dissenters.
See, the problem is Jesus never wrote anything himself. The four gospels provide conflicting views about him, but in today's world where Christianity is established with a strong base this doesn't really matter. Whether Jesus said, "My God, My God, why have you forsaken me?" (Mt.27:36, Mk.15:34) or "Father, into your hands I commit my spirit" (Lk.23:46) isn't really important to us. But in early Christianity when people were faced with a hostile, dominant, pagan religion, they had to defend their beliefs. And when you do this, you have to face deep questions about your faith. Like, what is the exact relationship between Jesus and God? In John it implies a coequal relationship, but in Mark he's definitely the inferior one. And if Jesus is divine, doesn't that make Christianity a polytheistic religion? That's why Christianity developed this idea of the Trinity — three substances but one being — to counteract the accusations that they weren't actually monotheistic. But there were some people, like the Arians, who rejected the Trinity and said Jesus was just a normal man. Then how did he obtain his powers? Did God just bestow his divine powers on Jesus during his baptism, as was seen with God's dove and voice (Mk.1:10-11) and then take them back when Jesus was on the cross, which is why he asked God why he was forsaken? And if Jesus is just a dude, why are we even considering him at all? Should we just ignore him and focus on God? What was the point of him? And if God did this once, couldn't he do it again?
These types of tricky questions were sprouting all over the place, which was causing problems in the church leadership. There were people in Antioch saying Jesus was just man, people in Egypt saying he was only divine (they actually said Jesus didn't die on the cross at all but just handed it over to someone else and melted into the crowd), and people who said he was both. And the Bible wasn't providing any answers because of its contradictions. That's Constantine tried to force a standardization because he knew interpretation of the text wasn't going to help.
But the ancients had another problem that we don't today: The Bible itself wasn't standardized either. Nowadays we have the four gospels, Acts of the Apostles, Pauline letters (half of which are spurious), other letters, and the Book of Revelation. That's it. But before there were tons of books floating all over the place and because Jesus didn't write shit and people didn't have the techniques we do today to ascertain veracity, no one could dispute it. You have a gospel saying it was written by Mary Magdalene. Who can refute that? Or just recently they've dug up the Gospel of Judas.
So basically what happened is the more powerful members of the church cut away any scripture that didn't agree with them. It was a gradual progress, but thanks to efforts by Constantine and church fathers like Jerome or Clement, we have a list that no one even questions anymore. And they were kinda right because some of these have teachings we find really fucking odd. For example, my favorite line from the Gospel of Thomas is, "And Jesus said, 'Any man born of a woman is the son of a whore.' "
Which finally leads me to my point: Gnosticism. I said in the beginning Christianity, regardless of the sect, is more or less similar with superficial differences like having bishops or not. When you examine Presbyterianism and Catholicism, they seem the same when compared to Gnosticism. That's the fucking weird one of the bunch. I don't even consider it part of Christianity and think of it as a separate religion. But they thought of themselves as Christians and had the scriptures (which other Christians didn't accept) to prove it. Now, before I talk about Gnosticism I need to give a disclaimer: Because it never took off, it never became consolidated like Christianity did. There is probably no group that believed everything that I'm about to say. They picked and chose. But the general theme is there.
Gnosticism is the answer to two questions: Why is God in the Old Testament completely different to God in the New Testament? And more importantly, why is there suffering in the world? Their creation myth answers this. In the beginning there was a good god. There's varying reasons why, but Wisdom suddenly appeared and wanted to have sex with this god. When he rebuffed her, out of her anger she created another, inferior god that is called the Demiurge. The Demiurge thought it was the most powerful being in the universe, not realizing there was a better god out there, and out of its own arrogance it created the world to prove how awesome it is. After some time the good god realized what was going on and sent his son, Jesus, down to the people to explain the truth of the matter. That's why the gods are different: The Demiurge is the god of the Old Testament, and the good god is the god of the New Testament. For Gnostics, the Old Testament is just wrong altogether and is not in their canon (they weren't the only Christian sect at the time to reject it). And that explains why there's evil in the world: A fucked up god could only inevitably create a fucked up world. If the actual good god created all of this shit, we wouldn't have wars, disease, earthquakes, starvation, etc. And propagating just continues the the cycle of suffering. For Gnosticism, the end game is all of us die. They didn't believe in reproduction. We have to destroy everything until we all return to the good god.
Gnosticism was a rival to mainstream Christianity, particularly in the east like Egypt or Syria. Augustine himself was a member of a sect called Manichaeism before he switched over. Thanks to Constantine the Roman government clamped down on them, but it probably continued in smaller communities underground until Islam came. And it sprung up again in the 1100s and 1200s in southern France by a group called the Cathars. No one knows why Gnosticism suddenly became a thing when it was quiet in western Europe for centuries, but I can say the power structures in Europe freaked the fuck out and actually sent a crusade. Yeah, there weren't just crusades going over to the holy land. They were headed straight to southern France and they wiped that shit out. That's why it's called the Spanish Inquisition as opposed to just plain "Inquisition." Because it actually started in southern France to root out these Cathars and the Spanish just asked later if they could hire that shit for their own country.
When I look at Gnosticism or any of those scriptures that didn't make it to the canon, I wonder sometimes what could've been. The Gnostics are definitely the weirdest of the bunch, but there were all other sects of Christianity: the Ebionites, the Marcionites, the Nestorians... How would the story of Christianity have played out if they had a more prominent role? In America we just focus mostly on Protestantism and Catholicism, but there still are vestiges of these early sects out there, particularly in the Middle East where unorthodox followers fled after being persecuted in the Roman Empire for heresy. I doubt Gnosticism would've risen in a big way considering its ultimate message of death, much like how the Shakers are dying out due to their beliefs in complete celibacy, but in the ways it could've influenced Christianity. Today some scholars see a mirroring between the Demiurge and the good god and Christianity's Satan and God.
And when people complain to me about Catholicism's idolatry or Protestantism's penchant for following an egotistical charismatic leader, I'm totally cool with that. There's weirder shit out there. And if that's how you want to express your religion, then fucking go for it. Because there's no "true" Christianity. If the earliest Christians were dealing with this type of shit that's more complex and heterogeneous than anything we have today, I doubt there ever was a "true" Christianity. You can see it in the Bible even. Peter and Paul did not get along because Paul was a late comer. And people were spreading rumors about Paul that you see in his letters. This shit was never unified and it never will be.