An examination of what the Early Church Fathers wrote about various topics.
One thing is clear. All these doctrines developed over time, some radically so. Many were simply non-existent early. Others were present in an embryonic form early but didn't blossom for centuries.
The modern Catholic teaching of transubstantiation was not taught by the Early Church Fathers. The following factors were present very early ...
These factors didn't appear until later ...
Conclusion: The Eucharist was passed-down by the apostles and it was more than merely symbolic (as many Protestants teach).
The concept of the priesthood developed along with the Eucharist.
The modern Catholic doctrines of the papacy do not appear early. It is true that the Roman church was considered to be a source of orthodoxy, perhaps because Peter and Paul fashioned this church to be orthodox. But at first, only the bishops of Rome insisted that the "pope" (bishop of Rome) had powers beyond other bishops. After this, bishops started to agree (but many didn't). The Orthodox church never agreed.
An early interpretation of the "Peter the rock" passage ...
Conclusion: The Catholic view of the papacy developed significantly over time but its seeds appear very early.
The idea that there is to be a church hierarchy developed rather early. By the time of Cyprian of Carthage, it is fully-developed.
The sacramental system with 7 sacraments did not appear early. Certainly the word 'sacrament' appears early but seems to merely mean the concept that physical objects in some way can have a role of the way in which God graces us. Baptism appears very early in the writings of the Early Church Fathers and is clearly a sacrament. The other sacraments are later developments.
Some aspects of baptism appear very early ...
Conclusion: The Protestant notion that baptism is merely an act done in obedience is false. Baptism is a sacrament and results in the remission of sins for those who are properly disposed.
There was no sacrament of matrimony in the early church. This developed later. All marriages were considered to be permanent and divorce was not allowed (except in the case of adultery, or a non-Christian spouse who left a new convert to Christianity).
Conclusion: The Catholic Church developed the idea that marriage is a sacrament much later.
No evidence from the Early Church Fathers.
Conclusion: This doctrine developed slowly. Today there are differences between the Catholic view and the Orthodox view.
It is true that ministers were acknowledged as being validly ordained via the laying-on of hands by fellow bishops. However, this was not considered a sacrament until much later. The purpose of acknowledging who was a valid church leader was to preserve sound doctrine. Bishops were ordained by fellow bishops and there was no pope until much later. Bishops were selected by their local congregations. There were bishops who were not ordained until long after they were considered bishops by their congregations.
Conclusion: Much has changed regarding ordination since the times of the early church. These modern teachings of the Catholic Church were not merely handed-down by the apostles. The early flexibility has since become very rigid and formalized.
There was no such sacrament until much later.
Conclusion: The Catholic Church added the idea that anointing of the sick is a sacrament much later.
The Catholic sacrament of confession does not appear in the early church. Here is what does appear ...
Certainly there was no sacrament of confession (reconciliation) via a private confession to a priest as is now taught by the Catholic Church.
Did the church pass-down the teachings of the apostles (and, therefore, of Jesus)? It would seem that at least until 200 A.D. the church could be trusted. See ...
The Catholic Church claims to have handed-down the teachings of the apostles. Certainly some of the teachings of the Catholic Church are those which were handed-down by the apostles, but many are not. For example, the doctrine of the assumption of Mary was not handed-down from the apostles.
Origen, in 185 - 254 A.D., specifies which particular doctrines were passed-down by the apostles. His list doesn't contain the various doctrines specific to the Catholic Church. Yet he seems to indicate that all current doctrines of his day were passed-down by the apostles. This implies that all the others were added later. His list contains only those which I consider to be essential doctrines.