Philippi was no backwater but the strategic "crossroads of the world." Originally Krenides ("fountains"), a gold- and silver-mining center, it was renamed in 356 BC by Philip II of Macedon, who saw its value commanding the valley and the Via Ignatia, the Roman road carrying nearly all land traffic between Asia and Rome. The decisive battle of 42 BC between Octavian and Antony and Brutus and Cassius was fought nearby over control of that road. Octavian then made Philippi a Roman military colony, and later Augustus raised its status to Colonia Augusta Julia Philippensis. Colony status was rare; Athens, Thessalonica, and Amphipolis lacked it. Colonists enjoyed autonomous government, immunity from tribute, and treatment as if living in Italy. They were stubbornly Roman in language, dress, customs, and titles, which explains the charge in Acts 16:20 that Paul taught customs unlawful for Romans. It also explains Philippians 3:20: Christians are colonists from heaven, an outpost whose citizenship is there. Paul chose Philippi deliberately, and God sent him to the foremost city of that part of Macedonia, though not the largest. The first converts spanned the social scale: Lydia, a wealthy merchant from Thyatira; a slave girl; and the Roman jailer. God was calling people of all nations and classes to unify them into one family, the Kingdom of God. The congregation was organized with bishops and deacons, poor yet generous, and shared a bond of affection with Paul stronger than any other church.

Philippi was not large compared to Corinth, Athens, or Thessalonica, but it was a Roman colony, which made it one of the key cities of Greece. Its importance came from its location on the main trade route, the Via Egnatia, between Rome and the nations to the east, about ten miles north of the northern Aegean. Travelers could ship out across the Aegean or continue east into Asia Minor, Syria, Palestine, and Babylon. God directed Paul there, where the gospel could reach many kinds of people through the city's commercial traffic. Its first converts spanned the social range: Lydia from the upper strata, the Philippian jailer from the Roman middle class, and probably the slave girl at the other extreme. The colony consisted of about 300 retired army veterans, with their families, who were settled on land and expected to do everything Roman and represent Rome. Paul draws on this in the letter as a parallel for Christians, who are citizens of a kingdom whose capital is in heaven and who are a colony representing it, conducting their lives as that kingdom would have them. Paul had been persecuted in Philippi, escaping after the earthquake once the city fathers learned he was a Roman citizen. The Philippian church loved Paul, shared in his sufferings, supported him with gifts, and prayed for him, unlike the Corinthians. Their one real problem was disunity, with cliques stirred up by two women.

Philippi was a relatively small city, yet unlike the larger Thessalonica, Corinth, and Athens, it was a Roman colony, meant to be an extension of Rome in which everything followed Roman tradition, law, custom, and dress. Its colonists took such pride in this that they became more Roman than Rome. Paul draws on this when he tells the Philippians to let their conduct be worthy of the gospel: as members of the church of God, begotten by God's Spirit, they are a colony and outpost of the Kingdom of God planted in Philippi, with a higher citizenship whose politics are in heaven. The Philippian church held a special place with Paul, who was its apostle, and the affection between them was deeper than he shared with other congregations. The city had no synagogue, as Lydia's conversion at the riverside prayer place shows. Paul was imprisoned and stoned there, and the believers witnessed this and then suffered the same conflict themselves from external adversaries, probably Jews, who may have pressed in from Thessalonica and Berea. The congregation was zealous, and its only real problem was a disunity growing out of a disagreement between Euodia and Syntyche, which Paul addresses by urging unity in the truth.