Traditionally, as in AV, twenty‐one of the NT documents have been entitled ‘epistles’, though modern translations prefer ‘letters’. The sense in which they are letters has been much discussed. For generations, they were regarded primarily as doctrinal and ethical treatises, setting out permanent guidelines for the Church down the ages, to which were added opening salutations and closing greetings; though of course it was recognized that they were sent to particular Churches or groups of Churches and read out to the assemblies.
In the 20th cent. the tendency was to emphasize their status as typical letters not unlike others written in the Graeco‐Roman world e.g. by Plato or the Cynics. Some of the Greek words are those found among the papyri discovered in Egypt and therefore with meanings of the 1st cent. rather than of classical Greek of 5th‐cent. BCE Athens. The papyri were for the most part trivial everyday letters and business communications but they have indicated that the epistles of Paul were genuine letters, though others, such as that to the Hebrews, were of a literary rather than ‘occasional’ character. However, even the ‘occasional’ letters of Paul have been shown to conform to some extent to the types and styles of letters of this period, as convention dictated. There was no model in the OT or in Judaism for the NT collections of letters.