Perhaps one of the most debated issues in New Testament studies is, What are the Gospels? What type of literature are they? Are they some kind of history writing? Are they biographies? Are they legends--or even just plain fiction?
Scholars have debated all these possibilities, and more, over the last few decades, and there is no absolute consensus emerging from the debate. There is, however, a growing trend to see the Gospels, or at least some of them, as some form of ancient, not modern, biography.
What is the difference between an ancient and a modern biography? A modern biography, say, Carl Sandberg's celebrated biography of Abraham Lincoln, is in general a womb-to-tomb recounting of a person's life. In the wake of modern psychology, there is often a focus on early childhood influences in order to explain later facts about and tendencies in a person's behavior and career. There is a concern to offer up something reasonably comprehensive, not leaving out any significant portion of, or episode in, a person's life. There is also a concern for a certain amount of objectivity, though of course absolute objectivity is never attainable. In addition, there tends to be a strong underlying belief that human personality develops over time.
If the last paragraph is a reasonable synopsis of the nature of modern biographies, it must be said at once that they differ markedly from ancient biographies. For example, ancient biographies do not strive for comprehensiveness; their concern is with character. Ancient biographers, such as Plutarch or Tacitus, would focus on selected episodes from a person's life because they believed those episodes revealed that person's character. The goal was to reveal a person's character and personality through indirect portraiture--through a recounting of some of a person's words and deeds. The biographers felt no compulsion to chronicle the person's whole life. Nor did most ancients share our modern belief in character development. They believed you were born and died with a certain character, though its real nature would only be revealed over the course of one's lifetime.
It is fair to say that the Gospels of Matthew, Mark, and John (but not Luke's, which is Part One of a two-part historical monograph) would have been seen by their first readers as biographies of the sort familiar to them at the time (that is, ancient biographies). Clearly enough, the focus is on Jesus from start to finish in these Gospels, and the big issue being raised is about his identity. Equally clearly, the Gospel writers let us know in one way or another that their presentations are not meant to be comprehensive (see, for example, John 20:30). We should not judge the genre of these Gospels on the basis of modern criteria about what a biography must look like.
The Gospels have sometimes been called Passion Narratives with long introductions. This description is basically an apt one, because almost half of each Gospel is spent just on the last week of Jesus' life. While modern biographers would see such a presentation as lacking balance, the ancients were fine with such lopsidedness, especially if there was something uniquely revealing about the person that happened during the particular time depicted. In the case of Jesus, the nature of his death required a lot of explaining, for crucifixion was not seen by anyone as an honorable or noble way to die. Indeed, Jews believed that people being crucified had been cursed by God. The ancients also believed that how a person died often revealed that person's character. Thus, the Evangelists had to do some real apologetics to explain how Jesus could indeed be the world's savior and at the same time be crucified by the worldly authorities.
Finally, ancient biographies strove for a vivid and telling portrait of an important historical figure. They did not strive for absolute objectivity; indeed, more often than not, ancient biographies were a form of advocacy or a tribute to the great man or woman in question. An example is Tacitus' tribute to his father-in-law Agricola.
At the end of the day, we must remember that biographies, whether ancient or modern, are more like portraits than photographs. They are self-consciously presenting a certain interpretation of a person's life from a particular angle. In the case of the Gospels, the interpretation involves the assertion that Jesus was the Christ, the Son of God, as the episodes in his life and his words are thought to reveal. The question this leaves us all to decide is whether the Evangelists have offered us interpretations that illuminate or obscure their subject matter. In my view, they reveal the truth about Jesus, rather than cover it up.