How was christianity spread throughout the roman empire soon after the death of jesus?

 It was because the presence and way of Jesus in their midst created a community like the world had never seen. These words from the Book of Acts are kind of a summary of the description of the early church. They devoted themselves to the apostles' teaching ''to the way of Jesus , to the way of Christ'' and to the fellowship ''They gathered to learn; they got to know each other; they got real; they confessed.'', to the breaking of bread and to prayer. Everyone was filled with awe by what God was doing in their midst. They became so generous there were no needy persons among them. ''Acts 2:42-47''

St. Peter and St. Paul introduced Christianity to the Romans.

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