One of the enduring myths about the Christian religion is that it effectively sprung uniform and whole as if like Zeus from Mt. Olympus. Sure, there were a few minor squabbles, but the religion that later became one of the world's largest, to all intents began as one more or less monolithic entity.
In fact this is a fairy tale that has no real scholarly support. What I'd like to do here is to provide a kind of concise history of early Christianity, up to about 300 AD. Most of the content has been extracted from some notes on Early Christian History (from Loyola) as well as the recent books: The Gnostic Gospels and Adam, Eve & The Serpent (by Elaine Pagels), and Lost Christianities, by scholar and former fundamentalist, Bart Ehrman.
The intent here is not to badmouth Christianity or diminish it, but to show it in its historic light, as opposed to the (often) fantastic, and ahistorical light many have used to portray it.
One of the aspects that most stands out is it's eclectic nature. Contrary to being a font for monotheism, early Christianity was anything but. Nor had the "god Man" claim for Jesus yet become entrenched, as it did later (mainly compliments of Paul) in the institutional religion.
In terms of the eclectic nature, Prof. Ehrman points out (op. cit.) that "some of the early Christians believed in one God, some in two, and some others in thirty". He also expressed the divergence of belief concerning Jesus:
"There were some who believed Jesus' death brought about the world's salvation (likely the precursors of evangelicals who wouldn't appear in full bloom for another 17 centuries, and others who thought it had nothing to do with it. Others said Jesus never died. We examine here some of the chief Christian voices-groups in the early centuries."
Perhaps the first were the Ebionites, and also the earliest of the banned sects, later to be called "heretics". This group believed in Christ but saw him as the Jewish Messiah, sent from the Jewish God to the Jewish people in fulfillment of Jewish scriptures. This take (of Ehrman) also comports with that of Oxford Scholar Geza Vermes, who notes (in his monograph ‘The Authentic Gospel Of Jesus’ (page 415):
“The religion revealed by the authentic message of Jesus is straightforward, without complex dogmas, mythical images or self-centered mystical speculation. It resembles a race consisting only of the final ‘straight’ – demanding from the runners their last ounce of energy and with a winners’ medal prepared for all the JEWISH participants who cross the finishing line."
Vermes goes on to observe (ibid.) that Christianity seems to "belong to another world, with its mixture of high philosophical speculation on the triune God, its Johannine Logos mysticism, and Pauline Redeemer myth of a dying and risen Son of God"
But why express surprise here? The fact is the myth of a redeemer god -Man had been in the cultural -religious zeitgeist (for example with the Mithraic pagans) for over twelve centuries. If a new faith wanted to claim exclusivity or unique gravitas and "separate from the pack" so to speak, it couldn't do better than to appropriate the same god -Man myth then weave it into its textual accounts(though not very well, as noted in the earlier Yale lecture on the New Testament I linked):
In addition, Jesus for the Ebionites was not a member of an eternal Trinity, but rather an ordinary man who kept Jewish law to perfection. As for their sacred text - accepted by them- it excluded the Gospel of John (which many current biblical historians have trouble with as well, partly for its elaborations - like on the trial of Jesus - which no other synoptic gospel discloses) while it retained most of the Old Testament and the Gospel of Matthew.
It's also noteworthy here, that the Ebionites - like the Gnostics- had a particular dislike for Paul, and also like the Gnostics viewed him as "the enemy" for his claim that all of Jewish law was rendered irrelevant by belief in Christ.
The Marcionites were another early Christian group, founded by a shipping magnate, Marcion, ca. 139 AD in Rome. Here, in this manifestation, we find the first appearance of the "double God", later circulated also by the Gnostics. The Marcionites thus accepted the world was created by an "evil God" (the one described in the Old Testament, in his various assorted genocides etc.) and that this evil god imposed a death sentence on humanity when it could not meet its impossibly high demands. In juxtaposition to the evil god was the "God of Jesus" and by belief in him, humans could escape from the vindictive wrath of the evil god. Those who did not, would remain in the evil god's clutches and join him in hell. (Again, we find exact resonances of this in modern evangelical Christianity who worship the same evil God in the OT. At least I've never heard or seen any of them reject him!)
Perhaps the most developed Christian group at the time, with the most refined philosophy and belief system, were the Gnostics. At least a few scholars speculate in fact that Gnosticism is at least partially an offshoot from early Greek philosophy. To summarize the Gnostic take:
'The world is essentially a cesspool and we're all mired in filth and ignorance. We all came from somewhere else, and salvation is finding our way back."
Like the Marcionites, the Gnostics believed an evil and inferior god ruled over the world (and also created our bodies). They called it demiurgos. Existentially, it was roughly on a par with Satan. So the evil god and Satan formed an evil twin duo. Gnostics, in terms of their scriptures and what they believed, penned their own "Gnostic Gospels". They rejected the Old Testament as antiquated rubbish about the demiurgos, while they rejected much of the New Testament because of the Pauline wording corruptions, and references to Jesus as "savior". They believed none of this was original, but the work of Paul's copyist henchmen.
Their core belief was that at the last instant of manifest existence a higher, supreme God would appear and insert into each of us his spark of divinity. At this stage, we would each attain a high enough level of knowledge (gnosis) to conquer our attachment to material reality and become Christs unto ourselves.
Thus, in the Gnostics, we see the first emergence of a totally different version of "Christ" from what Paul taught and circulated. Pagels observes ('The Gnostic Gospels', Vintage-Random House, 1979), p. 124 :
"While Pauline Catholics taught a reality of 'sin' and that 'Jesus alone could deliver healing and forgiveness of sins', the Gnostics on the contrary, insisted that ignorance, not sin, is what involves a person in suffering. The gnostic movement shared in this certain affinities with contemporary methods of exploring the self through psychotherapeutic techniques."
"Whoever remains ignorant... cannot experience fulfilment. Gnostics said that such a person 'dwells in deficiency'. For deficiency consists of ignorance."
Perhaps the most daring, and threatening proposition of the Gnostics, was their belief in gnosis, or the 'de-localization' of Christhood. Why? Because if the (Institutional-doctrinal) Church accepted this, they'd have to surrender their coveted power wielded via intermediaries (priests, bishops, cardinals, etc.). Paul knew this full well, which he fought against the Gnostics' egalitarian Christhood with all his might. There was no way he'd accept that every human could bcome a Christ in his own right.
Pagels echoing the principle of gnosis (ibid., p.134):
"Whoever achieves gnosis becomes no longer a Christian, but a Christ."
Even today, Gnostic churches exist, despite Paul's effort to wipe them out. In Barbados, a large Gnostic church still remains not far from the Constitution River in Bridgetown. When I last visited, at least three members declared that they were nearly at the level of "Christhood".
In effect, in the Gnostic teachings, anyone had the capacity to become 'a Christ'. Pauline Catholicism, meanwhile - held there could be only one, on which all others had to depend for 'salvation'. The Gnostics, for their part, regarded the Pauline teachings of a unique god-Man as utter blasphemy. NO mere human (which they regarded Jesus) could also be God, but each human could eventually become a limited divine manifestation known as Christ. (They did allow Jesus might have reached that stage before other humans)
Pagels goes on (ibid.):
"We can see, then, that such gnosticism was more than a protest movement against orthodox Christianity. Gnosticism also included a religious perspective that implicitly opposed the development of the kind of institution that became the early Catholic Church. Those who expected to 'become Christs' themselves were not likely to recognize the institutional structures of the church -its bishops, priests, creed, canon, or ritual - as bearing ultimate authority."
For this reason, As Pagels notes (p. 102), the Catholic orthodoxy and tradition (including many Church Fathers such as Tertullian- the original theocon) saw fit to consistently denounce the Gnostics "while suppressing and virtually destroying the Gnostic writings themselves." And of course, we had the likes of the unscrupulous idiot Irenaeus calling them 'frauds'. (Pagels, p. 17) To serve his own purposes of course!
One is left to wonder, why - if the Church and St. Paul felt so self-righteous, they had to destroy and suppress the Gnostic gospels and writings. Was their Church so weak and tepid that it couldn't co-exist? Seems so. Just like today's evangelicals are evidently so weak and tepid that they can't tolerate and co-exist with other Christian groups.
In any case, by the 4th century AD the early eclecticism had nearly vanished and an institutional Pauline Chrisitianity ended up the prime descendant of the original teachings and a religion which had essentially succeeded in wiping out or supressing all groups not centralized in Rome. The major turning point was undoubtedly the "Edict of Milan" which removed all penalties for professing Pauline Christianity. The latter subsequently achieved immense strength as it became the official religion of Rome, thanks to aligning itself with many elements of the Roman Sol Invictus (Sun worship) cult including adopting the same date for Its Nativity: the Winters Solstice or Dec. 25th. The rest as they say, is history, though historians such as Edward Gibbons have linked the decline and fall of the Roman Empire to its uneasy integration with the Pauline variant of Christianity. (See Gibbons: Decline and Fall of the Roman Empire)
Readers curious as to why the Vatican sought to keep most of the Dead Sea Scrolls - including the Nag Hammadi and Qumran texts - under its control without any other inspection by outsiders, should consult: 'The Dead Sea Scrolls Deception by Michael Baigent and Richard Leigh, Summit Books, 1991.