“None of the Gospels (or any other New Testament books) can be considered a missionary tractate for evangelizing pagans. Before ca. A.D. 125, early Christian literature was written exclusively for Christian consumption.”
This quote is from The New Testament in Its Literary Environment (1987) by David E. Aune, the Walter Professor of New Testament at Christian Origins at the University of Notre Dame. (Google Books preview; Amazon page)
Aune is cited frequent in Larry Hurtado’s Lord Jesus Christ: Devotion to Jesus in Earliest Christianity. For more on Hurtado, search “hurtado” on this blog.