Which of Paul's letters were written first?
Paul's first letters were 1st and 2nd Thessalonians, followed probably by Galatians and Romans, and then perhaps the Corinthians. These early letters were written close together, while the later epistles came toward the end of his ministry. This order is not the same as their order in the New Testament.
Les explains that all of Paul's letters are not in chronological order in the New Testament, nowhere near it. He states that 1st and 2nd Thessalonians were written first, then probably Galatians and Romans, and then perhaps the Corinthians, all pretty close together. Later, the prison epistles—1st and 2nd Timothy, Ephesians, Philippians, Colossians, Philemon, and Titus—were written toward the end of his ministry. Les also emphasizes that in every available manuscript, Paul's letters always appear in the same order as our New Testament, confirming the Holy Spirit's control over Paul's apostleship.