Paul's letter to the Philippians was likely written from prison in Rome, around 60. When he was first brought to Rome, he met with the leaders of the Jews, at which time he said "I am bound with this chain" (Acts 28:20). In the first chapter of Philippians, he says that he is "in chains for Christ" (Phi 1:13).
He was writing to the church in Philippi, a Roman colony in Macedonia that he had visited in his second missionary journey about AD 50. Paul had been at Troas in what is now NW Turkey, when he experienced a night vision of a man from Macedonia asking him to come to them (Acts 16:9). Paul visited several towns along the north edge of the Aegean Sea, prior to going to Athens.
Philippi was a Roman colony, inhabited mainly by ex-soldiers and Gentiles. There were few Jews, not enough even to form a synagogue. Here again, we see Paul's impulse to carry the Gospel to the "fringes" of the world, beyond the Jewish Diaspora. The account of his short, tumultuous visit to Philippi is told in Acts 16. A woman named Lydia was converted, and Paul and Silas lodged with her. But not for long -- Paul cast a spirit of divination out of a slave girl, upsetting her owners, who hauled them before the magistrates. They beat them and cast them into prison. It was in Philippi that the famous midnight earthquake occurred, breaking the chains and freeing the prisoners. When they did not run off, the terrified and relieved jailer (who was doubtless a Gentile) tended to the wounds of Paul and Silas, then listened to the Gospel message and was baptized. The authorities then freed the two men.
Only then -- after the mob action, the beating and the imprisonment, did Paul tell the officials that he and Silas were Roman citizens! This is amazing -- it means they voluntarily (and unnecessarily) endured the lash. And then, on top of that, to sing about it! Does this same spirit still inhabit modern believers?
Philippians is a short letter, with little racial teaching, but what there is is significant. One of the most important elements of it is what he does Not mention. In the entire letter, there is nothing about the Old Testament, the Law, Moses or Abraham. The righteousness of faith, the power of Christ's resurrection -- these Paul talks about as central to his life, and by inference, to that of his readers -- but no vestige of the Old Covenant. Truly,
Therefore, if anyone is in Christ, he is a new creation; the old has gone, the new has come! (2 Cor 5:17 RSV).