Paul.
The apostle Paul spread Christianity throughout the Mediterranean regionSaint Patrick spread Christianity throughout Ireland!
Many cultures are responsible for the spreading of Christianity. The main culture which spread it was certainly the Roman Empire.
I believe that this would be Paul. Because of his insistance in preaching the gospel, and even though he was a Roman citizen he was put to death.
Saint Thomas the Apostle was traditionally believed to be a carpenter before becoming one of Jesus Christ's twelve apostles and spreading Christianity after his death.
No culture is 'responsible' for Christianity. Christianity is based on the death, burial and resurrection of Jesus Christ.
The Apostle Paul (formerly known as Saul) witnessed the martyrdom of St. Stephen. He approved of Stephen's execution and went on to become one of the most influential figures in spreading Christianity throughout the Roman Empire.
Bloodshed.
I think we can't really know the answer to this. The Bible tells us about the missionary activities of Peter also Paul and some of his co workers but we don't know what other disciples were doing. Another Answer: St Peter and Paul the Apostle
Spreading Christianity
But they most certainly were and Paul was their specially appointed Apostle by God.
The Apostle Paul
Andrew the Apostle is considered one of the Twelve Apostles in Christianity and is known for being an early disciple of Jesus Christ. He is credited with spreading the teachings of Jesus, particularly in Eastern Europe and Asia Minor. Andrew's most significant contribution was his role in laying the foundation for the Christian faith through his missionary work and martyrdom.