Since the 4th century we read the New Testament starting with the four Gospels, followed first by the Acts of the Apostles, and second by letters of the Apostle Paul of Tarsus. This order is nevertheless incorrect and should be read precisely the opposite way. Changing the order of lecture would allows us to better understand how the "biographers" of Jesus were influenced, positively or negatively, by what was first produced and disseminated: the letters of Paul. We would also be able to see how one depends of the other if we put Mark in the first place, as it should be.
Why were the Gospels made? What is the exact meaning and use of this term? Is the literary figure of "gospel" something invented by the Christians? How did the change between the purely spoken transmission of Jesus' facts and words to their writing occur? Did the evangelists copy each other? The study of the Gospels has to take into consideration the interest each of them has as a separate unit, on top of considering what is their aim as a group. Could the Gospels be assigned to the different groups that were formed after the death of Jesus? Are they a positive or negative reply to the doctrine of Paul? Was there any need to establish and justify a differentiation from Judaism, the common cornerstone from which the religion of the first christians stemmed? Did any of the Gospels intend to solve the difficulties that involved the creation of a new group, like for example the delay of the end of the world that was initially believed to happen immediately, or the destruction of the Temple of Jerusalem and the end of sacrifices?
Once we locate the Gospels as a block within the evolution of the different Christian groups following the death of Jesus, we need to briefly address each of them separately, focusing in the main aim each of them had.
The writings of Mark follow the catastrophe of year 70 with the destruction of Jerusalem. Was Mark conditioned by this fact? His he really loyal to all his references? Or alternatively, does he include in his "story" his own interpretations or the interpretations of the group to which he belonged? Matthew shows quite some differences from Mark due to an intentional plan for reworking the material he has in front of him. It is like a new edition, extended and corrected, of the Gospel of Mark. The Gospel of Luke presents a diverse world in comparison to the other two synoptic evangelists, even if it is only because of the fact that it is not a single "gospel" like the other two, but it is composed by two parts. The second part, which is inseparable from the first one, are the Acts of the Apostles. For Luke, the time of Jesus is really something in the past, a different time of the Church in which he lived. This implies that the evangelist has a new conception of history, which will define how the evangelist receives, changes and adapts the tradition.
The tradition of the Church presents the Fourth Gospel as the work of John, son of Zebedee, one of the Twelve, but this fact is nowadays discarded. When comparing the Fourth Gospel to the other three, we find very significant differences that pose important interpretation difficulties as it presents a very different image of Jesus. It is necessary to attempt providing an explanation to this fact, at least partially: the enigma of the existence of this Gospel so different from the rest.