Paul cast a demon out of a fortune-telling Philippian girl who was being used by her owners for gain (Acts 16:16–18). Her owners thus accused Paul and Silas of 1) being Jews, 2) disturbing the city, and 3) promoting customs unlawful to Romans (Acts 16:19–21). Paul and Silas were sorely mistreated as a result (Acts 16:22–24). Interestingly, even though they were falsely accused (the owners’ real concern was their loss of income), Paul and Silas, both Roman citizens, did not bring attention to their Roman status in order to receive a fair trial and avoid being beaten. But Paul shamed their captors over the matter later (Acts 16:35–40). Why did Paul not speak up at first but only later point out his Roman citizenship?
The answer to this question is found in Paul’s reply to the command to leave in peace. He pointed out their Roman citizenship, that they had been beaten unfairly and publicly, and thus refused to be released secretly (Acts 16:37). Fearing discipline from their own higher-ups on the matter, the magistrates were forced to give Paul and Silas an apology and personally release them from the prison (Acts 16:38–39). This apology and release would have been more or less a public “walk of shame” that admitted their wrongful treatment of the missionaries.
This being said, it seems that Paul and Silas said nothing of their Roman citizenship at first so as not to argue for their Roman status over against the gospel. It would have sounded something like, “Charge us with what you’d like, but we are Roman citizens. So, you cannot thrash us.” While that would have been good and fine for them, where would that have left the newly converted Lydia and her household? They could still be targeted, and persecution could have wilted the newly budding Philippian church.
As to why Paul finally spoke up in prison, he and Silas were already on record for being willing to suffer for the gospel. Now, in making the magistrates publicly admit their wrongful treatment, while the city at large was not converted to Christianity, the people would at least see that their officials were now being civil to the Christians. Perhaps Paul had this effect of the public apology in view. The Philippians obviously had an initial bias against whatever they viewed Christianity to be, but now they would have to tolerate the Christians and would be less likely to treat them as they did Paul and Silas, especially as the two would leave soon leave the city (cf. Acts 16:40).
As Christians today, perhaps we can learn from Paul and Silas that we should use wisdom when invoking any privileges to avoid persecution. We should defend the gospel itself before we defend ourselves, and we should also defend other Christians from civil mistreatment if it is in our power to do so.