Christianity began with the indwelling of the Holy Spirit on Christ’s followers gathered in an upper room in a home in Jerusalem. It was from this moment on that the spread of Christianity took root with Peter and the other disciples speaking to the people gathered for the Jewish festival of Pentecost.
There were three major factors that helped prepare the way for the swift spreading of Christianity. The first of these factors was the large gathering of Jews in Jerusalem for the festival of Pentecost. Over time many of the Jews had spread out far and wide away from Jerusalem. These Jews were called Diaspora Jews, meaning they had dispersed. When they heard Peter’s message, of the life Jesus, many believed and became saved. Those same Jews then left Jerusalem back to their far away homes and spread the gospel to those in their area.
The second major factor is that of the Roman roads. It was a true statement that all roads really did lead to Rome. As many people, from many religious backgrounds and cultures, used these main roads it made for an efficient route for the story of what had been happening in Jerusalem. Merchants traveling these roads from town to town would have also spread the story of what happened in Jerusalem to their other import and export towns.
The third major factor was the rise of Greek philosophy and thinking. The teachings of Plato and Socrates spread wide, and left many with open minds to other religions and thoughts of the supernatural. This open mindedness toward other ways of thinking made a way for the apostle Paul to share Christ as not just another god among many, but as the one true God who became flesh.
These three factors largely contributed to the preparation for the quick spread of Christianity from the town of Jerusalem to the rest of the world.