In the early stages of Christianity we find that there were more options to the newly formed Christian Church then just the Catholicism that we’ve heard about. There were branches of it that the Apostle Paul talks about in his epistles as ‘teaching something other then the true way.’ The way was what Christianity was called during the times of Peter, Paul, and John although those are the only beliefs we hear about and many are given the false impression that was all there was at that time either
Peter and Paul’s form of Christianity, or complete non-Christianity such as Judaism and the Greek and Roman polytheistic systems of religion. That couldn’t be further from the truth. There were not just the Catholics, Peter and Paul’s religion, but also what we today have called Ebonite, Marcionism, Montanism, and Gnostic. These all posed as a threat to the Catholic way of Christianity.
The largest one of the smaller branches was by far the Gnostics (Gnostic is based on the Greek root word gnosis meaning knowledge). They were far and away the largest Christian based religion under the Catholics. The Gnostic Church based it’s religion on the love and teachings of Jesus trying to emphasize knowledge and learning about God , where the Catholics based theirs on faith, the resurrection, and obedience to God in a much more familiar way to the Jewish beliefs to begin with.
Seeing the Gnostics as a treat but unable to truly do anything about them for literally hundreds of years, the Catholics were faced with the much more imminent problem of the Roman Empire trying to do away with all of the Christian churches mostly due to the fact that in the Roman Empire Caesar was considered God. If others believed in a God different to Caesar they would not be as obedient to the Empire and this could create pockets of resistance that would need military assistance to keep the piece. For many of those years the early Christian religions would need to stay hidden or face the wrath of Caesar. We have all heard the stories of crucifixions, being fed to the lions, or beheadings. After the conversion of Emperor Constantine by his mother in 312 AD, he changed the official religion for the first time away from the old Caesar is God belief to the Christianity we know of. His mother was converted into Catholicism so as a mostly political move, Emperor Constantine changed the religion that they had not been able to get rid of for almost the last 300 years.
Finding that the new religion was also branched into different denominations that also disagreed on very major levels, he ordered the Council of Nicea to happen in 325 AD. What happened next was a political move. To make sure the two major denominations were represented, Constantine ordered 318 members to attend from both the Catholics and the Gnostics. The count was 306 Catholics and 12 Gnostics. The Catholics made all of the decisions and ordered the Gnostics, all of their members, and all of their sacred writings to be destroyed. Since the winners write the history books, and the Catholics now had the same army that had been killing them for hundreds of years now behind them, Gnosticisms faded off until today after archeological findings have brought their works back to life.
The Council of Nicea also decided much of the dogma of the Catholic religion that we still have to this day. With opposition out of the way it was much easier to get beliefs of Jesus as God incarnate and the belief of Hell passed into the doctrines we have today.