How did the whole then-known world hear the plan of salvation in Paul's lifetime without mass media?
Roman soldiers guarded Paul during his house arrest in Rome and rotated in and out of duty. As they were reassigned across the empire, including Caesar’s palace, they carried the message. Paul ministered to these guards, and those who spent time in his house became believers, spreading the plan of salvation throughout the then-known world.
Les explains that Paul’s ministry lasted only about thirty years—he was converted around 37 and put to death in 67—yet Scripture says the whole then-known world, primarily the Roman Empire, had heard the plan of salvation. He points to Paul’s house arrest in Rome, where Roman soldiers guarded him twenty-four hours a day. Because the Roman army rotated soldiers, many guards likely served at Paul’s house over those two or three years, two, three, or four at a time. As they were rotated out to the far reaches of the empire, and even into Caesar’s palace, they took what they had heard. Les says anyone who spent time in Paul’s house left a believer, so through Paul’s ministering to his guards, who then went into service throughout the empire, the whole then-known world heard the plan of salvation.