The beginning of the Christian church is popularly thought to have started during Jesus’ life, or at least upon his death when Saint Peter was named the first pope in A.D. 33. Yet most scholars agree that this early Christian church did not become a fully fledged independent institution until several hundred years later, at the first Council of Nicaea in A.D. 325.
The Council of Jerusalem
Only a few short years after the death of Jesus, the Bible records that very early Christians called for a meeting of all apostles and elders in the new religion: the Council of Jerusalem. Held around A.D. 50, the Council of Jerusalem was supposedly the very first formal gathering by Christian leaders, and is sometimes considered to be the true beginning of the institutionalization of the early Christian church.
The Apostolic Age
Before Constantine called for the first Council of Nicaea, the early Christian church was only loosely organized and included several distinct, and sometimes contradictory points of view. Christians in each area were taught subtly different teachings about Jesus and the church in general, and there was very little consistency between Christians who lived even moderate distances apart from one another. During this Apostolic Age, so called because of the great commission called by Jesus for his apostles to spread the message of Christ throughout the world, the Christian church could hardly be called an institution. Most other religions considered Christianity a minor heretical Jewish sect, and rightly so. There was very little cohesion among Christians of this early era.
Emperor Constantine the Great
The first stirrings of the institutionalization of the early Christian church was due to Flavius Valerius Constantinus, who was born to a Christian mother who taught him much about her individual brand of faith. When that child later became emperor of Rome, he never forgot those early teachings and would eventually decide to convert to Christianity, bringing the religion to all of Rome along with him.
This was a paradigm shift for the still young Christian religion, and it quickly became clear that a council of some sort would have to be held, so that the wide disagreement on views between the elders of the church could finally be worked out.
The First Council of Nicaea
The first Council of Nicaea was ordered by Emperor Constantine in A.D. 325 to consolidate what would be considered the true views of Christianity and to properly brand all other views as officially heretical. This Constantinian shift marked the true beginning of the institutionalization of the early church and finally legitimized what had once been considered itself a minor heretical sect of Judaism into a religion all its own.