In a recent comment posted on this blog Cedric Katesby asked the question "Who were they [i.e., the writers of the New Testament] and why would they be in a position to know?" It is a very good question indeed, and one that is basic to the truth claims of Christianity. How well documented are the events surrounding the earthly life and ministry of Jesus?
We have already given a partial answer to the question in two previous blog posts, "Are the Gospels Historically Reliable?" (1/1/12) and "How Do We Know that Jesus Rose from the Dead?" (1/5/12). It may be pertinent here, however, to add a few more details, especially concerning the so-called "Synoptic Gospels," Matthew, Mark and Luke.
So then, who were the "evangelists," or authors of these three gospels? Matthew was one of Jesus' twelve disciples, a former despised tax collector who had occupied the bottom rung of Jewish society. According to early church tradition, Matthew originally wrote his gospel in Hebrew or Aramaic at the time that Peter and Paul were preaching in Rome. It was later translated into Greek by others.
John Mark apparently came from a well-to-do family living in Jerusalem. His mother was a committed Christian, and Mark himself became a close associate of several early Christian leaders, including Barnabas, to whom he was related, Paul, Timothy, and Peter. According to tradition he was prevailed upon by others to put Peter's testimony in writing, and the result was our present gospel that bears his name.
Luke was a Gentile and a physician, and a travelling companion of the apostle Paul. A well educated man, he could show himself capable of writing polished Greek.
To get to the second part of Cedric's question, "Why would they be in a position to know?' the short answer is that Matthew was an eyewitness, Mark recorded the testimony of an eyewitness, and Luke had plenty of access to eyewitnesses. Undoubtedly what occasioned the writing of the gospels was the fact that the apostles were starting to pass from the scene, and it was necessary to get their message down into writing.
What is especially interesting is the fact that there is an obvious literary interdependence to the synoptic gospels, in some cases right down to the very wording. The more conventional modern view is that Mark was written first, and that both Matthew and Luke used Mark as one of their sources. Matthew and Luke also presumably had at their disposal a collection of Jesus' sayings. This other document is usually designated "Q," or "Quelle," the German word for "source." The theory, however, has all the characteristic shortcomings of modern scholarship. It dismisses the testimony of the early church fathers, and relies instead on a highly subjective reading of the texts themselves, along with a hypothetical reconstruction of events. In short, it gets rid of the evidence and replaces it with conjecture. There is no historical evidence that any such document as "Q" ever existed.
If the information that has been handed down to us from the early church is correct, however, Matthew was written first, and then Mark and Luke a short time after, viz., at about the time that Peter and Paul were martyred at Rome (ca. A.D. 64). Those would mean that Mark apparently used Matthew as one of his sources, possibly the Hebrew or Aramaic original, alongside what he could remember about Peter's preaching. In condensing Matthew's account, Mark edited out the portions of Matthew that were primarily of Jewish interest, such as the lengthy discussions of Jewish law. What he presents us with is the gospel for the Gentiles. Luke then probably used both a Greek translation of Matthew along with Mark, as well as a variety of other sources.
This circumstance tells us something significant about all three of the gospels. Luke was a well-educated person, and he tells us in his prologue that his aim was "to write . . . an orderly account" so that "you may know the certainty of those things in which you were instructed" (Lu. 1:3,4; NKJV). If he used Matthew and Mark as his sources, what this tells us about them is that Luke thought that they were authentic accounts of the earthly life and ministry of Jesus. And what it tells us about Luke himself is that he was a skillful historian who handled his sources carefully. Significantly he does not appear to have injected his own theology into the narrative. As a close associate of Paul, he might have been expected to recast Jesus in a Pauline mold, a preacher of justification by faith as opposed to works of the law. But he did not. Luke went only as far as his sources would take him, and the picture of Jesus that emerges in his gospel is that of a controversial Jewish rabbi Who claimed to be the Son of God and the Messiah.
At the time that these three gospels were written there were still many persons alive who had heard the apostles firsthand, and in some cases even Jesus Himself. They could easily have corrected any mistakes in the narratives. (The closest we come to a "correction" is the Gospel of John, which supplements rather than corrects.) All four gospels found ready acceptance by the early church, which was well aware of the existence of spurious gospels and could tell the difference between the false and the true.
Thus the life and teachings of Jesus are, in fact, remarkably well documented. We know today as much about Jesus as we do about anyone else in ancient history.