For 2000 years Christians have accepted that the four Gospels provide reliable historical facts about the life of Jesus. They also accepted that the ancient historians provided reliable accounts regarding the origins of these Gospels. Borrowing had obviously taken place between the authors of Matthew, Mark and Luke, later known as: ‘The Synoptic Gospels’. Who had borrowed from whom was of little academic interest until 1764 when Henry Owen, an Anglican Vicar, proposed that Mark wrote after Luke.
Although discussed in Germany, conservative scholars rejected the idea because it contradicted Jerome’s sequence of Matthew-Mark-Luke.
But Owen had arrived at his theory by critically examining the wording used by the authors, and this prompted others to also do so. In 1838 Christian Weisse claimed that as Mark’s Gospel was in poor grammatical Greek, compared to the other two, he must have written prior to them. His reason was that the ‘borrower’ would not deliberately turn good quality Greek into poor quality. The sequence that Mark wrote first became known as the Markan Priority Theory.
Rationalists and other non-believers in the German Universities, supported by the government, championed this theory because all the ancient historians had said that Matthew wrote first. The acceptance of Markan Priority would mean all the early Christian historians were seriously wrong so unreliable.
Also, they could argue, that as most scholars dated Mark as writing about 64 AD, Matthew and Luke must have been written much later. So, these Gospels would have been authored by anonymous individuals who had never met Christ. They would have constructed stories of Christ not based on facts but on their personal faith.
Such a lack of Scriptural reliability would devastate Evangelical Christianity. And the evidence for the historical claim, by the Catholic Church, to having been founded by Christ would be undermined.
Christians answered those promoting Markan Priority [In future here referred to as Markans], by basing their stand on the words of the historians and on the reliability of Jerome’s listing in the order of Matthew, Mark, Luke and John. But although they undermined the Markan position, they failed to win the debate convincingly.
On the other side, Markans found it necessary to rely on an alleged historical document they called Q – although there was not the slightest historical evidence that it ever existed. The two sides fought each other to a stand-still.
Then, in 1965, the Second Vatican Council maintained that the historians were correct. It restated that the eyewitness Apostles and their apostolic friends had authored the four gospels. Soon afterwards, research led to a third theory emerging (or re-emerging), which would reconcile modern critical analysis with the historical evidence.