I recently came across this short but interesting piece by NT scholar Ben Witherington entitled, “Latinisms, Western Diction, and the Provenance of Mark’s Gospel.” Despite the jargon-loaded title, certainly not designed to attract any lay people’s interest, it’s worth a read by non-specialists since it provides a succinct description of the kinds of clues scholars detect in biblical books that provide guidance in discerning the circumstances of a book’s authorship, occasion, and audience.
Most Bible students have heard or read things like “the gospel of Mark was intended for a Gentile, not Jewish, audience.” It’s easy for the lay person to wonder what oracle was consulted for that sort of information. But the reality is that texts do drop distinct hints that shed light on such things, or rule out certain possibilities. Not all biblical books have useful information as to authorship or audience or circumstances, but some do. The gospels fall into that category.