The apostle Paul wrote 13 letters to young churches, pastors, and friends in order to guide, encourage, and correct them. Most of these letters served a specific purpose or addressed a specific question or problem.
Nine of the Pauline writings were sent to churches; four to individuals. Most of them deal with problem situations then existing in the churches (Ephesians seems to be an exception). Some are very personal in tone (Philippians and 2 Corinthians); others appear to have a more formal, almost thesis-like style, and in their main features (excluding the usual personal introduction and conclusion) show a rather businesslike tone. Romans would probably be the outstanding example of this type. Further, the letters of Paul show great variety in content, and also combine doctrinal and practical components in good balance.