The Book of Acts records or reports that there was a special event that took place at Pentecost, which would have been the next pilgrimage festival after the Passover at which Jesus died. And at that time the disciples of Jesus were gathered together in Jerusalem unsure of what their future would be, when all of a sudden the spirit took hold of them and enabled them to speak in tongues, and that speaking of tongues is understood by the author of the Book of Acts to mean speaking in all of the languages of the world. So with the power of the spirit behind them, the disciples of Jesus immediately began a missionary campaign and started bringing people into the fold, converting them to belief in Christ. And from that time forward the mission moved ahead in the rather smooth way, directed by the spirit and by all of the apostles who acted in concert with one another and agreement with one another. That's the picture that we get in Acts. The historical reality is probably much more complex.
Christianity, or one would rather say "Christianities," of the second and third centuries were a highly variegated phenomenon. We really can't imagine Christianity as a unified coherent religious movement. Certainly there were some religious organizations.... There were institutions developing in some Christian churches, but only in some. And this was not universal by any means. We know from, for example, the literature recovered at
Nag Hammadi, that gnostic Christianity didn't have the kind of clear hierarchy that other forms of Christianity had developed. They still clung to a charismatic leadership model. And so there was a lot of variety in 2nd and 3rd century Christianity....
There were very different views of Jesus in the various types of Christianity.... Perhaps the starkest contrast was among those who considered themselves as gnostic Christians, and those who considered themselves Christians in the old Pauline view of things. On the one hand,
Paul, and Pauline Christianity, would have placed all of the emphasis on Jesus' death and resurrection, and the saving power of that death and resurrection. Gnostic Christianity, on the other hand, would have placed its prime emphasis on the message, the wisdom, the knowledge, the gnosis, that's where the word gnostic comes from, the Greek word for knowledge, the knowledge that Jesus transmits, and even the secret knowledge that Jesus transmits. So one would have on the one hand faith in the saving event of Jesus' life and death, and on the other hand knowledge as the great source of adherence to the Jesus movement on the other hand.
More on the gnostics.
http://www.pbs.org/wgbh/pages/frontline/shows/religion/first/diversity.html