There is some debate when it comes to the dating of the Gospels. Some would like to date the Gospels in the 50s or 60s. There are others who will argue vehemently that the earliest Gospel must have been written after 70 AD.
The most popular dating of the Gospels puts Mark (as the earliest Gospel) at 70 AD or slightly before, Matthew and Luke in the mid-80s and John in the 90s. But let me tell you a secret.
We don’t really know.
So where do these dates come from?
The early dating of the Gospels is based on some backward calculating from events in Acts. Acts ends with Paul in Rome but still alive. Paul was executed around 65 AD during Nero’s reign. Assuming that Luke (who wrote Acts) would have described Paul’s death if it had already happen, Acts is then dated before 65. Luke’s Gospel is then dated before that. Since most scholars assume that Luke used Mark, that puts Mark fairly early.
However, we don’t know why Luke didn’t describe Paul’s death. It may be because it had not yet happened or he may have had some other literary or theological reason not to mention it. We don’t know.
The later dating of the Gospels revolves around a historical event in Jerusalem. It was in 70 AD that the Romans destroyed the Jerusalem Temple. The Synoptic Gospels include a prediction by Jesus of the destruction of this temple. Since it is impossible for people to predict the future, the Gospels must have been written after the destruction in 70 AD. Some scholars will let Mark be slightly before the event, when it was obvious that something like this would probably be happening.
Would the Gospels have to be dated after 70 AD? Since I’m a Christian, I don’t see it as impossible that Jesus could have made such a prophecy.
However, from a historical perspective I don’t think that the Gospels have to be dated after the destruction. From a purely human point-of-view, it is possible that Jesus could have successfully predicted the destruction of the temple. The tensions that led to the Jewish War of 67-70 were already present in Jesus’ day and it would not require divine sonship to predict that something was coming. In terms of the details of the prediction, Roman military practice was not a secret. Jerusalem was not the first rebellious city that the Romans destroyed. Jesus could have easily described what would happen to Jerusalem.
I appreciate the honesty of New Testament scholar Larry Hurtado in his commentary on Mark:
“For our purposes, we shall allow for the writing of Mark any time between A.D. 50 and 75, as I see no compelling basis for being more precise here.” (p. 8)
The truth is that we don’t know when the Gospels were written. We can place a beginning point as the last event described (death and resurrection around 30-33 AD) and an ending with our earliest manuscripts or quotations from these Gospels in other writings.