Wenham, John. "Chapter Eleven: Jesus-Tradition Oral and Written." Redating Matthew, Mark, and Luke: A Fresh Assault on the Synoptic Problem. Downers Grove, Illinois: InterVarsity Press, 1992, 217-222.
Wenham's overall argument leads toward an early date for each of the Synoptic Gospels. Despite the existence of the texts, it is fair to ask why the rest of the New Testament does not refer to them directly (Wenham 1992, 218). Wenham does observe that there are indicators throughout the New Testament of knowledge of the traditions about Jesus, even though there is very little overt reference to those traditions. In fact, explicit references to the written Gospels are also rare in the Fathers, whose knowledge of the documents is not in question (Wenham 1992, 219). For that matter, in Acts, Luke does not repeat the events of his Gospel to explain what the apostles are doing. Wenham views the purposes of the Epistles to be significantly different from those of the Gospels, thus requiring different types of information and proofs (Wenham 1992, 220). There is a presupposition of knowledge about Jesus, but the events of the Gospels are not used as direct arguments.
Wenham further considers that cultural differences between Judaism and Christianity made the use of written normative documents less important in Christian communities than in Jewish communities (Wenham 1992, (Wenham 1992, 220-221). These differences were based on an emphasis on orality rather than textuality in Christianity, as well as a focus on apostolic authority rather than canonicity.