Epistles

While the term is often used in books and commentaries as a synonym for letters, Adolf Deissmann—on the basis of a comparision of the vast numbers of such ancient literature found among the papyrus—makes a distinction between them. Letters are what we think they are, pieces of private communition written to specific people regarding specific issues, greetins or instructions; they are not intended for publication. Epistles, Deissmann proposed, are different in that they are intended to be broadcast and published for public consumption.

James and 2 Peter, in Gordon Fee's opinion, "are the closest writings in the New Testament to 'epistles' (that is, tracts for the whole church), although 2 Peter seems to have been called forth by some who were denying Christ's second coming (3:1-7). James, on the other hand, so completely lacks an overall argument that it looks more like a collection of 'sermon notes' on a variety of ethical topics than a letter."

The most important thing to remember when reading and interpreting the letters and epistles of the NT is that they were all occasional in nature, i.e., while there is much theology in them, they were originally written in reponse to specific needs. It is vital to keep this historical context (and, therefore, the cultural background) in mind when reading them.

Further Reading & Resources:

Gordon D. Fee & Douglas Stuart, How to Read the Bible for All Its Worth. 4th ed., Grand Rapids: Zondervan, 2014. If you have never done any study in biblical interpretation before, this is an excellent book with which to begin. On the letters and epistles, see esp. pp.57-92.