After the original disciples of God completed their missions of preaching the new good news of the Gospel all around the known world (mostly in the Roman empire but some might have went farther east out of the roman empire into Mesopotamia, Scythia, and even as far as India ), then making disciples of these new believers, and establishing a local Christian church in the area and continuing to teach them what they were taught and the Jewish Tanakh/ warning them to not stray away from what they were taught by them. They said their goodbyes to the churches they helped to establish and died (many died by being killed in persecution from the local natives/government) leaving the newly established churches completely on their own around about 90 A.D. with selected elders in charge of the local groups.
After around 100 A.D. or so the former leaders of the false Christian groups that claim to have taught a truer but more ‘secretive’ or ‘hidden’ Christianity had grown significantly through the decades by deceiving Christians, Jews (that is followers of Judaism: mostly ethnic Jews at this time), and pagans alike.
By 100 A.D., All these different individual movements became known as “Gnosticism” (meaning “Having [hidden] Knowledge” in Greek) because though all movement believed/taught slightly different things all of them had one major thing in common:
They all claimed that the original church the disciples originally founded were not teaching the full truth to reality/salvation nor did the Bible directly teach the total truth: rather The Bible was ‘hiding’ the truth in symbolism and code that the disciples/Christians did not understand but that certain individuals had ‘found out’ this hidden secret of The Bible that only they (and their followers) knew and taught: and only through this secret knowledge (not through accepting Jesus sacrifice) could someone be saved.
Along with this one major belief they also had common doctrines many Gnostics movements had in common:
Almost all of them believed Father God (as found in the Bible) could not be truly known by any human because he wanted nothing to do with the physical universe and what was in it. Rather, Father God created other spirits that eventually became evil and then they created the physical universe (including planet Earth and all life on it; including humans) and therefore all physical things in this universe are also evil because their creator(s) are evil, and a human could only know these evil spirit creators (who were often called ‘the lesser gods’) personally and not Father God. They also believed the physical body of humans was evil but humans also had a spirit within them that was good and that God did not want their spirits/souls coming to the spirit realm once they died, so one of his spirit helpers came to earth (some Gnostics say this was Jesus but others might say their individual founder was this spirit) to tell them how to get to this spirit realm that was trying to block their spirits from entering after death.
It told them how a human spirit could be saved was to learn this ‘hidden’ or ‘secret’ truths of the Bible/Gospel it taught:
this would ultimately free their spirit inside of them when they died so they would be able to enter into the spirit realm [1].
All this of course clearly contradicted pretty much everything the disciple taught the churches they had established, and even what the newly written Bible (composed of the Jewish Tanakh: called now ‘the Old Testament’ and the newer gospels written by the original 12 disciples of Jesus and their other writings called ‘The New Testament’) said:
Which clearly said that salvation can only be found through Jesus’s sacrifice (as opposed to this ‘secret’ knowledge):
Acts 4:12
“Salvation is found in no one (or nothing) else, for there is no other name (or anything else) under heaven given to mankind (Humanity) by which we must be saved.”
The Bible also describes God as wanting to have a direct relationship with humanity and it being very possible to know God and even have a direct (or indirect) relationship with him by encountering him in visions/dreams, speaking to him in prayer and having him answer back (as covered in detail in “The importance of prayer”), having his holy spirit lead you/ being inside of you, and even just reading his word (the Bible) to know more about him ( as opposed to it being completely impossible to know him or even have a relationship with him).
And possibly most contradicting thing of all to what the disciples originally told the church/ what they could find through the Bible now was that God directly created the physical universe and especially the Earth and everything on it (as opposed to another spirit being creating it):
Genesis 1:1
“In the beginning God created the heavens and the earth.”
John 1:2-3
“...God…Through him all things were made; without him nothing was made that has been made.”
The original churches that were founded by the disciples recognized that all these other movements lumped under the new ‘Christian denomination’ of Gnosticism was a false Christianity just like the disciples originally told them they were that directly contrasted and even warped what the disciples taught and the entire Bible itself in a horrible and destructive way.
For this reason, the original churches rightfully did not consider followers of any Gnostic movement true Christians because of the direct conflict with what they were taught by both the disciples and Bible itself. And they constantly tried to fight against this deceptive movement that threatened true Christianity by burning their destructive writings up and church leaders often got into heavy debates with Gnostics over how Gnosticism was warping the Bible and deceiving Christians and pagans alike.
Through the 100’s A.D. many Christian leaders tried to ban Gnostics from the Christian community, condemning them (rightfully) for being deceitful teachers/followers that were helping to deceive/corrupt the church that wanted to stay loyal and correct as possible to the original true apostolic denomination. While they did successfully run off many Gnostic groups from the church community there was one major group in particular that they failed to run off and not only that was determined to take control of all of Christianity by blending their doctrines with Christianity by sneaking into the church and introducing their doctrines to the Christians to slowly take over and corrupt the church and ultimately pretty much all of Christianity.
They were none other than the Simonian Gnostics: one of the oldest (and several by now) gnostic groups founded by the deceiving and wicked Simon the Magician himself. These Simonian Gnostic ‘Christians’ had always considered themselves Christians though usually went by the name of their founder ‘Simon’. And like Simon it seems they had always tried to sneak into the main church community to deceive Christians, but many were found out and banished from the Church.
Throughout the later centuries, this particular group of Gnostics was for the most part was successfully avoiding detection from the leading Christians and were slowly deceiving all the Christians in these churches by slowly introducing their dangerous and destructive doctrines to them:
This is what Peter warned the church about:
false teacher slipping into the Christian community and introducing them to their destructive doctrines that would destroy true Biblical and apostolic Christianity!
As one loyal Christian Eusebius noted in his time (that would be around 300 A.D.) that these so called ‘Christians’ were massively slipping into the churches everywhere and slowly introducing their dangerous and destructive doctrines to them:
“Simon…he feigned and counterfeited faith in Christ, even going so far as to receive baptism…And what is surprising, the same thing is done even to this day by those who follow his most impure heresy. For they, after the manner of their forefather, slipping into the Church, like a pestilential and leprous disease greatly afflict those into whom they are able to infuse the deadly and terrible poison concealed in themselves.”[2]
The church tried to get rid of them all from corrupting them completely with their wicked doctrines, but sadly it seems they were not able to do so in time:
The Simonian 'Christians' ended up winning over most loyal Christian to at least some of their destructive doctrines: and so, at about around 400 A.D. true apostolic Christianity as it was founded was pretty much corrupted by a mixture of Simonian Gnosticism with the original apostolic Christianity making an entirely different Christian denomination that the original disciples warned the church about.
This is what Paul prophesized about: That one day the church would not want to accept apostolic Christianity (wherever by deception from other false teachers or willingly) and turn to false doctrines (like Simonian Gnosticism) that they wanted to hear or grown to like to hear:
After 400 A.D. this new Simonian Christian denomination eventually began to welcome back other Gnostic groups that were formerly banned from the community that seemed to get absorbed into this new ‘Simonian Christian’ denominational belief. Eventually throughout the centuries, Gnostic groups (and the denomination of Gnosticism itself) began to slowly disappear; most likely because they just became Christians and accepted this new ‘Simonian Christianity’: eventually almost all Gnostic groups became absorbed into this ‘Simonian’ version of mixed Christianity that forever corrupted mainstream Christianity and lead to a new and corrupted form of Christianity mixed with paganism and original apostolic Christianity that eventually became known as Catholicism (Coming soon).
Sources:
[1]
[A] Wikipedia “Gnosticism”
Website:
[B] Learn Religions “Gnosticism: Definition and Beliefs”
Website:
https://www.learnreligions.com/what-is-gnosticism-700683
[2]
From verse 12-13 section 1 Book 2 of “Ecclesiastical (church) history” by Bishop Eusebius of Caesarea in 312–324 A.D. by TOPOS texts (The Aikaterini Laskaridis Foundation) translated into English by Arthur Cushman McGiffert
Website: