One of the difficulties in teaching the methods to discern the mystery is that we are talking about solving riddles. There is not one way to solve riddles. There are hints and helps to get you started, but eventually the way you think must change to embrace the idea that there is a mystery concerning Christ to be solved.
To help set your mind in the proper frame, consider that the Gospels are a commentary of the Old Testament in light of what the disciples knew about Christ and what was taught by him. Do not think that the authors were writing something new, or that they miraculously were given knowledge.
Their testimony is that Jesus fulfilled scripture. Do not expect that there are details just to add flavor to the Gospels, but that the details are part of the fulfillment of prophecy in the OT.
Consider that the Greeks did not wish to be Jewish, and they did not want to learn all that Jewish stuff. They just wanted to be Christians, so Paul was teaching them only about the cross. [1] As time passed, most of the apostles still taught in Hebrew among the Jews. Do not suppose that they were unaware of each other's teaching. The teaching of Peter captured in Mark was the teaching of all the apostles being related to the Greek church. Later Matthew captured a snapshot of the teaching of the apostles; then Luke and John.
Each snapshot captured how the apostles had learned to discern the mystery better with time and with the tools they discovered. They were not instantly made capable of reading the whole mystery. they studied to show themselves approved. [2]
Purpose of the Gospels
The primary purpose of the books were to relate the 'current trends' in apostolic preaching, to the Greeks who did not want to know too much Jewish stuff. The Gospels were transmitted by couriers, who, at least in the first distribution, likely sat under the teaching of the apostles. It is likely that the letters were not full dissertations on apostolic thought, but 'Cliff' notes which could be filled in by the courier. The great number of traveling teachers may be evidence of this practice of filling in the details of the teaching from the outline of the gospel.
For this reason is was not required that the gospels explicitly stated every reference to the OT scripture. Many knew the scriptures well and would likely be able to make associations easily.
The differences in the Gospels will highlight the growth in their understanding of the mystery. From the differences we can discern if the growth was merely in the time spent discerning the more of the mystery, or if they obtained tools as they went to help them discern more.
The differences in the Gospels demonstrate that the ability to discern the mystery can be learned. There can be no doubt that their writings were intended to teach us how.
Next: Mark Intro