What does Acts 18:4 mean?

Although Paul arrived in Corinth alone, he has settled into a routine. Silas and Timothy are in Macedonia and will join him before too long (Acts 18:5). Until then, Paul has met Priscilla and Aquila and joined their tentmaking business (Acts 18:2–3). On the Sabbath, Paul goes to the local synagogue.

Paul's modus operandi when entering a new city is to go to the synagogue on the Sabbath and wait to be asked to teach. He will then open to the prophets and show how Jesus of Nazareth fulfills the prophecies of the Messiah. His hope is that all the Jews, as one body, will come to faith in Jesus. Usually, however, some Jews and a larger number of God-fearing Gentiles will believe him, he'll get kicked out of the synagogue, he'll find a place outside the synagogue to teach, a lot of Gentiles will join, and the non-believing Jews will harass him until he leaves the city.

Paul finds the same cycle here in Corinth. After Silas and Timothy finally arrive, the Jewish leaders in the synagogue harass Paul to the point that he leaves. Fortunately, one of the Gentile God-fearers lives next door and invites Paul to teach from his home; the leader of the synagogue follows. Despite the harassment, God tells Paul He will protect him. Paul and his team stay for a year and a half, building the church (Acts 18:6–11).