First, as to an overview: Paul's fourteen letters seem to fall into five groups:

  • The earliest, 1 and 2 Thessalonians (and possibly Galatians), were written on his second missionary journey when he first went to Europe.
  • Romans and 1 and 2 Corinthians were written during his third journey, when he spent most of his time in Ephesus. (This was at the time of the troubles in Corinth, when Titus was sent there: 2 Cor 8:16,23; 12:18.)
  • Ephesians, Colossians, Philippians, Philemon and Hebrews were written near the end of his first imprisonment in Rome (Acts 28:30), when he was expecting soon to be released, as he indicated in several of them.
  • Titus and 1 Timothy were written in the period after his release, when he was back working in the same area of Greece, Asia Minor, and Macedonia again.
  • Finally, 2 Timothy was written, right at the end of his life, from prison again in Rome.

There are several different types of Pauline letters: 14 letters in all. Nine were written to seven ecclesias (if Galatians can be reckoned as an ecclesia) — there being two each to Corinth and Thessalonica. Just as Jesus Christ in the Apocalypse sent messages to seven ecclesias, so did Paul. (Seven is the Scriptural number of completion and perfection, suggesting that Paul's ecclesial letters contain the complete gospel and perfect instruction for all ecclesias.) Some of the nine ecclesial letters were written to answer special questions (as the two to Corinth); some to oppose special false doctrines (as that to the Galatians); and others to upbuild and strengthen generally.

From a different aspect, these nine ecclesial letters may be divided into three basic groups:

  • Four doctrinal: Romans, 1 and 2 Corinthians, and Galatians.
  • Three practical: Ephesians, Philippians, and Colossians.
  • Two concerning Christ's return: 1 and 2 Thessalonians.

Paul's five other letters were also written for several purposes. They consist of one thoroughly personal letter (Philemon); one general letter, to Hebrew Christians with dangerous leanings toward Judaism (Hebrews); and three letters to individuals (Timothy and Titus) who were leaders of ecclesias.