How did the spread of Christianity evolve in the later Roman period?
After Jesus died the early Christians developed bravery and fellowship together at first. But it is important to remember that they were only human and frail with weaknesses, and soon the challenges of jealousy and envy began to set in - perhaps triggered by the persecution of the Romans and the deaths of Peter and Paul and the ensuing power struggles. An early Christian, Clement of Rome, sent the Corinthians epistles requesting peace, faith renewal, and passing on the apostles' teachings.
There had been trouble when a set of younger Christian missionaries 'fired' some of the elders and people began to pick sides. Clement wrote to try to end the infighting. They may even have spied and informed on one another as Tacitus reported that there were times when Christians were arrested because of intelligence given by rival Christians.
Clement's letter was read out in the church of Corinth as part of the early Christian liturgy year after year and all across the Roman world. The irony is that Jesus was proven right in his predictions of human conflict in the coming millenia--even amongst those he had trained and warned of the temptations they would face in carrying out his work throughout the empire of Rome and beyond.