The letters to the Philippians, Colossians, Ephesians and Philemon are known as the 'captivity epistles' because in each of them Paul appears to refer to the fact that they were written while he was in prison. Apart from that, they are all very different. Philippians is written to a church with which Paul had close ties, and about which he had no serious worries. Colossians addresses a serious threat from false teaching, while Philemon is a personal letter about a runaway slave, and Ephesians is a letter of general encouragement and exhortation, addressed to several churches. One theme shared by all the letters, however, is that Christ may be served whatever our human circumstances. Christians must see their own place in the world as their opportunity for worship and service, whatever it may be. Part of The People's Bible Commentary. The People's Bible Commentary (PBC) is designed for all those who want to study the scriptures in a way that will warm the heart as well as instruct the mind.