It has been argued, and rightfully so, that there existed a strong oral tradition in first century Judaism. But, what should that mean to us in the 21st century? Should we believe that no one wrote anything down concerning Christian literature prior to 70 CE except for Paul during this period of oral tradition? Certainly Josephus didn’t let his Jewish history to oral tradition and he drew upon the writings of others who recorded what Jewish officials were doing at the time the events transpired. So, other Jews, who also held to a strong oral tradition, were recording events of importance in written form.
Luke seems to suggest in the opening lines of his Gospel that written material about Jesus circulated side by side with the oral tradition of the day. Notice:
Luke 1:1-4 AUV-NT Your Excellency Theophilus: Since so many people have undertaken the task of compiling a narrative of events that have happened among us, (2) [that is, people] who were ministers of the word and original eyewitnesses [of these events], and who passed them on to us; [and since] (3) I have thoroughly investigated the entire series of events [myself], I felt it would be good for me also to write you an orderly account of them. (4) Then you could know how reliable the information is that you have been told.
Luke mentions is verse-1 above that before he even attempted to write his Gospel many had already written orderly accounts of what was believed among those of the Jesus Movement. These written records existed side by side with what Theophilus knew through oral tradition (Luke 1:4). Notice also what Luke says about the value of the written record, however. In Luke 1:3 he claim that he had composed a written record of these very things, so Theophilus would have in his possession a hard copy of the oral record, showing or proving its reliability! In other words, the written document was considered more reliable than the oral account, which could be forgotten or deliberately changed by enemies of the Jesus’ Movement.
If this is a correct understanding of what was presumed by folks in the 1st century CE, I find it incredible that the narratives about Jesus teaching and public ministry would not have been written down by the believers who wished to protect the Gospel’s veracity. This understanding of the value of the written record over the oral would be very compelling to establish the written record very early. Why would the Apostles have waited decades to write anything down about Jesus, if they understood the written record was more valuable than the oral tradition?
If the written records of what Jesus said and did were not an afterthought of the Apostles, the argument that all or some of the Gospel narratives weren’t written until after the destruction of the Temple and Jerusalem becomes much less compelling. It is only because modern critics assume the 1st century church didn’t understand the value of a written record over the oral tradition that it is assumed that the Gospels were written late. Nevertheless, Luke shows this isn’t so. Many had already written orderly accounts of what Jesus had said and did (Luke 1:1).
One of the strongest arguments for all the Gospels to have been written before 70 CE is their failure to mention the destruction of the Temple and Jerusalem. Although some critics would argue that the prophetic account of the Olivet Prophecy in the Synoptic Gospels could be seen as written after the fact, yet this would say nothing about the Gospel of John. It makes no mention of the Olivet Prophecy. Why wouldn’t it record the destruction of the Temple and Jerusalem as an accomplished fact, if it had been written near the turn of the century as many presume?
The fact is prophetic sayings in all the Gospels seem to refer to something future. For example, Jesus had predicted his death and resurrection very early in all four Gospel accounts. Why wouldn’t we presume the Olivet Prophecy was recorded to show Jesus had predicted the fall of Jerusalem and the destruction of the Temple. The silence in the Gospels over the destruction of the Temple and Jerusalem “is as significant as the silence for Sherlock Holms of the dog that did not bark!”
 John A.T. Robinson, Redating the New Testament [1976; page 13].