The Early Church
The day of Pentecost (the birthday of The Church) produced the long awaited baptism of the Holy Ghost. It first fell on the apostles, and eventually encumbered a number totaling 120 that were gathered together in the upper room. The early church was not without a witness to the power of the Holy Ghost or the Name of Jesus.
After Peter preached his heart convicting sermon, 3000 souls responded, and were added to the church that same day. All that believed Peter's words were identified with Christ by being baptized into his Name, and were filled with the Holy Ghost. This set a distinct pattern for the early church that has come to be known (historicaly) as the Apostolic faith.
Any deviation from that experience was not considered to be valid by the early practitioners of Christianity. Yet, Paul warned that after his departure, sound doctrine would begin to erode as men would turn unto fables.
Some of the first known departures from the Apostolicity of the church were imposed on Christian believers during the first "Ecumenical Council" in church history - taking place at Nicea in 325 A.D. Although the theological argument at Nicea was not over the doctrine of the Trinity, but more about the diety of Jesus Christ... it did however, lay the ground work for a fully developed theology of the trinitarian doctrine, and, the soon adoption of its theological position into post-apostolic church history.
However, Nicea 325 A.D. did produce the first realized departure from the Apostolic doctrine of the apostles by changing the baptismal formula from, "into the Name of Jesus Christ", to the titles, Father, Son and Holy Ghost. This they say is the Orthodox position of Christianity. However true this might be, it is not the authentic position of the early church (30 to 325 A..D.) for this time period finds the church holding to the apostles doctrine of water baptism into the name of Jesus Christ. Modernist accuse anyone who does not embrace Othordoxy of practicing heresy. Anyone who promotes this ideology has disregard for the book of Acts, which is the history book of the New Tewstament Church. Even Pope Benedict XVI (Cardinal Ratzinger) admits that Catholicism takes responsibility for changing the baptismal formula from "In the Name of Jesus Christ" to the titles, "Father, Son and Holy Ghost." The second Ecumenical Council was held at Constantinople in 381 A.D., at which time the Roman Emperor, Theodious I, adopted the tenents of the Trinity, which had been fully developed between 325 and 381. Theodious I, made the Trinity a legal matter by adopting it as the state-wide religious view of the Roman Empire.