Perhaps, I might be a bit clearer. There were many, many different sets of beliefs in the Christian communities, especially before Constantine and the later book burning. Saint Paul cautioned against the influence of other teachers. Saint John dealt with this issue clearly. Jesus seemed to have dealt with the issue when he prayed that we all might be one. There were many, many writings being read in home churches throughout the first three centuries. There were many, many beliefs. To be clear, the Egyptian monks (the desert fathers and mothers) knew little about the niceties of theology. If they were better organized and more vocal, they probably would have kicked out also.
The approach of the very early Church was to debate and then kick out those who didn't agree. We have a different approach today. Many think that accepting those who disagree as fellow Christians.
ONE EXAMPLE - ARE MAN'S ACTIONS RELEVANT TO SALVATION -Must there be some cooperation with the Will of God?
The GNOSTICS taught that we needed to accept God in our hearts. The Word was inscribed in our hearts, and it was the condition of our hearts that was important. As individuals, we needed to become more conformed to God. It was not the Church that determined our eternal life; rather, it was God and our acceptance of Him. The Church was not very relevant to the Gnostics. Gnostics were kicked out of the Church and their books burned. Although the Gnostics had many misunderstanding of the faith, we do not kick out modern day Gnostics.
PELAGIUS and his followers taught that man must cooperation with God's gift of salvation. Salvation required more than the Will of God and the actions of the Church. Man's actions could affect our salvation. We were able to affect when we go to heaven or hell. Pelagius and his followers were kicked out of the Church. And through this day, it is almost an anthem to call someone a Pelagian or even a semi-Pelagian.
LUTHER agreed that we are saved by Grace. However, he also taught that man's actions were important. Man was saved by Grace through his faith in Christ Jesus. Excommunication was the penalty for these views.
WESLEY taught that we must have free will to choose or reject God. He was called a semi-Pelagian. Since he was a bit alter, he was not ex-communicated. After all, he was an Anglican priest his entire life.
And NOW the Roman Catholic Church understanding on this subject are really not all that different from the past heretics on the subject. To put it another way, the views of Pelagius, Luther and Wesley on this subject are well within the bounds of Orthodoxy, even if Catholics now understand the doctrine a bit differently.
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If we are to be true to the very early Church, we should consider almost all Christian faith groups as non-Christian. I think that this would be folly. Perhaps, just perhaps, it was folly then as well.