What does Acts 16:25 mean?

Paul and Silas have been imprisoned, wrongly, at least from a certain point of view. It is true they "advocate customs that are not lawful" in the Roman Empire (Acts 16:20–21). Specifically, they are spreading the worship of a deity—Jesus—that is not authorized by the Roman government. In truth, their accusers charged them for financial reasons. Paul expelled a demon from a slave girl. The girl lost the ability to tell fortunes, and her owners lost the ability to use her to make money (Acts 16:16–19).

Promoting the worship of an authorized god was a serious crime, but the city magistrates also broke the law when they beat and imprisoned two Roman citizens without trial (Acts 16:22–24). Paul and Silas don't know what will happen, but they know God is in control. Paul references this suffering in Philippi in his letter to the Thessalonians (1 Thessalonians 2:2). In that same letter, he will tell the Thessalonians, "Rejoice always, pray without ceasing, give thanks in all circumstances; for this is the will of God in Christ Jesus for you" (1 Thessalonians 5:16–18). And he will tell the Colossians that as Jesus suffered to offer salvation, he willingly suffers to spread Jesus' offer of salvation (Colossians 1:24).

Since Luke inserted himself into the narrative (Acts 16:10), the writing grew more personal and detailed. Verses 25–34 again feel impersonal and summarized. That doesn't mean this part isn't Scripture. Paul and Silas probably told Luke what happened, and the Holy Spirit directed him to include it. Verse 35 returns to the more personal, first-hand style (Acts 16:35).