This is a really interesting question! There is a development through the gospels, where the oldest focus on the actions, saying and prophecies of Jesus, while the newest (John) is much more focused on the divinity of the person Jesus. Paul seem quite uninterested in the words of Jesus and totally focused on the importance of the resurrection. So the transformation from teacher or prophet (a normal human speaking the words of God) into a some kind of divine being happened quite soon. To put is crudely, Jesus start out as a priest talking about the Gods plans, but over time, in the minds of his followers, turns into a God himself. But the full transformation into "God" was only finalized with the Nicene Creed in 325. Even now there are Christian denomination which do not believe that Jesus is God, most notable Jehovas Witnesses (which holds that Jesus was created by God, and therefore not God himself).
An important transformation is that the title of Messiah (or Christ in Greek translation) has a very specific meaning in a Jewish context, as a human king or savior of the Hebrew people. When early Christianity spread beyond Jews, this context disappeared, and the title "son of God" got reinterpreted in a Greek context, where gods could literally have children.
> "the full transformation into "God" was only finalized with the Nicene Creed in 325."
The Nicene Creed is one of the clearest statements of the "Jesus is God" hypothesis, but (as I said elsewhere in this thread) there are plenty of strong claims made in the gospels themselves. There are also similar claims made in many of the earlier writings of the church (if you're honestly interested, there are 10 pre-Nicene volumes at http://www.ccel.org/fathers.html .)
An important transformation is that the title of Messiah (or Christ in Greek translation) has a very specific meaning in a Jewish context, as a human king or savior of the Hebrew people. When early Christianity spread beyond Jews, this context disappeared, and the title "son of God" got reinterpreted in a Greek context, where gods could literally have children.