The Epistles of the Bible are the 21 books in the New Testament that constitute formal letters of instruction from elders to leaders and members of the new Christian church. Thirteen of the Epistles were written by the Apostle Paul, three by the Apostle John, two by the Apostle Peter, and one each by James and Jude. The author of the Epistle to the Hebrews is unknown.
The 13 Epistles written by the Apostle Paul, also known as the Pauline Epistles, are usually placed in the New Testament after the Acts of the Apostles and followed by the Epistle to the Hebrews and then the rest of the Epistles. Romans, First Corinthians, Second Corinthians, Galatians, Ephesians, Philippians, Colossians, First Thessalonians and Second Thessalonians were written to churches, or groups of believers, in specific locations to address problems or concerns that come up. The other four Pauline Epistles, First Timothy, Second Timothy, Titus and Philemon, known as the Pastoral Epistles, were written to leaders of the church and gave instruction about how they could better oversee those in their care.
The remaining eight Epistles are known as the general, or Catholic, Epistles, as most of them were written as doctrinal admonishments not for specific groups of Christians but to Christians in general. The exception is the Epistle to the Hebrews, which was written to advise Jewish Christians to base their lives on the Christian doctrine of salvation rather than Old Testament law.