What does Acts 16:12 mean?
Paul and Silas leave Syrian Antioch to visit the churches Paul had planted with Barnabas on his first missionary journey. They make stops in central modern-day Asia Minor, picking up Timothy in Lystra. The Holy Spirit directs them to bypass northern and western Asia Minor. In Troas, Paul has a vision that directs them to cross the Aegean Sea, instead, bringing Jesus's offer of salvation to Macedonia. So, they pick up Luke and land in Neapolis, the port city of Philippi (Acts 16:1–11).In most cities, Paul enters the local Jewish synagogue and waits for the leadership to ask him to speak (Acts 13:5, 14; 14:1; 18:4). He shows how Jesus of Nazareth fulfills the Hebrew prophecies of the Jewish Messiah (Acts 13:16–41). Some Jews as well as some God-fearing Gentiles who worship the Jewish God believe him (Acts 13:43; 17:4). Eventually, those who do not believe him will run him and his followers out of the synagogue, and they will establish a church in a local home (Acts 18:7).
Philippi doesn't have a synagogue. It takes ten Jews to establish one, which tells us something about the demographics of the city. Instead, the team will go to the river, a common place for people to meet and pray. They will find Lydia, a Gentile who worships God, and lead her and her household to salvation in Jesus (Acts 16:13–15).
The lack of a synagogue means that Paul and his companions won't be pushed out of town by Jews angered by worship of Jesus as the Messiah: a man who claims to be God. Or, they may be jealous the missionaries' message is so well received (Acts 13:45; 17:5). But Philippi is a Roman colony, which comes with its own problems. The population is Roman. Most of the natives are Roman citizens. They live as if they are in Italy. One of the strongest laws is that it is illegal to preach about a god not recognized by the Roman government. Judaism is a recognized religion; to this point, Christianity is seen as a sect of Judaism. When Paul disrupts the business opportunity of local slaveholders, they will take advantage of their city's strong affinity for the law and have Paul and Silas beaten and jailed (Acts 16:16–24).
Their charge is true, but the magistrates make a terrible mistake: they assume two itinerant Jewish teachers are not Roman citizens. The crowd and magistrates who abused Paul and Silas are guilty of a greater crime than the evangelists and could, themselves, be imprisoned (Acts 16:35–40).