Paul founded the churches in Galatia under unique circumstances: he had fallen ill in this area and was nursed back to health by the Galatians; while he was recovering from his illness, he taught them about God and Jesus, and they converted.
Paul wrote the letter to the Galatians to counter the message of missionaries who visited Galatia after he left. These missionaries taught that Gentiles must follow parts of the Jewish Law in order to be saved. In particular, these missionaries taught that Christian men had to accept the Jewish rite of circumcision. According to Paul, however, circumcision was not just unnecessary, it was an affront to God. Paul insisted that Gentiles who submitted to circumcision were rejecting God's promise offered through Christ: a person is justified by faith not by works of the law. Paul's disgust at the Galatians is apparent in the form of the letter: it does not contain a thanksgiving.
Paul begins his letter of reprimand by affirming his authority and the truthfulness of his message. This aspect of the letter may suggest that the missionaries had attacked not only Paul's gospel but his authority as well. Paul insists that he is an apostle sent by God-that is, his authority does not stem from himself or from other humans. Thus, Paul argues that when the Galatians turned from his gospel to a new teaching, they had abandoned God and stood under a curse.
The major theological point Paul makes in his letter to the Galatians is that a person is justified through faith in Christ's death, not by works of the law. If the law could justify a person, then Jesus died for no reason. God gave the law as a disciplinarian until the arrival of Christ; it never justified a person. Ironically, however, Paul taught that Christians, who are not bound by the law, should love one another because in doing so they fulfill the law.
Philippians, like 2 Corinthians, may be a compilation of two or more letters. The first two chapters resemble a friendship letter: Paul writes to assure the Philippians of his own well being, as well as that of Epaphroditus, a member of their church. At the beginning of chapter three, though, the tone changes abruptly: Paul chastises those in the community whom he perceives as his enemies.
One explanation for the abrupt transitions in this letter is that at some point after Paul left the church in Philippi, he was arrested. When the Philippians learned of his plight, they sent him money through Epaphroditus. At this time, Paul learned of some problems in the community. He wrote to the church to thank them for their gift and to warn them against false teachers and divisions in the community (ch 3-4). While he was with Paul, Epaphroditus fell ill. When he recovered, Paul wrote another letter to assure the Philippians of Epaphroditus's health. In this letter, Paul reminded the church of his apocalyptic message and urged them to maintain unity in the face of schism.
Philemon is the only undisputed Pauline letter addressed to an individual. The letter concerns a runaway slave, Onesimus, and his master, Philemon. Onesimus committed some act against Philemon and fled to Paul in order that Paul might mediate between the two parties. Paul converted Onesimus, and wrote to Philemon to urge him to allow Onesimus to return, not as a slave, but as a brother. It may be, however, that Paul was not asking Philemon to manumit Onesimus but to give Onesimus to Paul for his own benefit.