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

At first, Christians were considered pagans and suferred persecutionwithin the Roman Empire, where they remained loyal to their politeistic cult.

This was the situation until the arrival of Emperor Constantine the Great to power, who ruled between the years 306 and 337 AD. He was the first emperor that converted to the Christian faith, almost in his deathbed. However, he had previously influenced the enactment of the Edict of Milan in 313, that implemented religious tolerance and the end of persecutions of Christians within the borders of the Empire.