From Craig Blomberg (Jesus and the Gospels: An Introduction and Survey, 2nd ed., pp 121-2):
What, then, is encoded in the texts of Matthew, Mark, Luke, and John to help us know how to interpret them on the "macro-scale"? Are they unadorned works of history or biography? Are they extended myths? historical fiction? In short, how do we assess the genre or literary form of an entire "gospel"?
When one compares the Gospels with modern biographies, vast differences emerge. Mark and John tell us nothing of Jesus' birth, childhood, or young adulthood. They devote almost half of their narratives to the events of the last few weeks of his life. Matthew and Luke add a few details from Christ's birth, while Luke narrates one event that occurred when Jesus was twelve, but nothing else appears before his adult ministry. In all four Gospels, to varying degrees, material is arranged topically as well as chronologically. The words of Jesus are paraphrased, abridged, explained, and recombined in a variety of ways. Little wonder that many modern scholars have looked for something other than "history" or "biography" to characterize the Gospels' genre.
Some of the suggestions that have been made involve "aretalogies" - Greco-Roman accounts of the life of a "divine man" that embellish or exaggerate the feats of a famous hero or warrior of the past. Others look to Jewish precedents and liken the Gospels to novels, perhaps at least partly historical. Still others use language of the theater and label the Gospels as "comedies" or "tragedies." Closely related is the identification of a Gospel as an "epic narrative." Some focus on the extensive use of the Old Testament (or the use by later Gospels of earlier ones as if they were sacred Scripture equivalent to the Old Testament) and identify individual Gospels as "midrash" (see above, pp. 43-44). One similar proposal thinks that Mark was a Christianized version of Homer's Iliad or Odyssey. The particularly cryptic character of parts of Mark has suggested to a few that the whole Gospel genre be considered a "parable" or an "apocalypse," while John's divergence from the Synoptics has led others to label his work a "drama."
These and related suggestions capture certain dimensions of the Gospels, but none accounts for a majority of their features. An increasing number of scholars, therefore, recognize that the list of traits setting the Gospels apart from modern biographies does not distinguish them nearly so much from ancient Greco-Roman biographies or Greek and Jewish "historiography" (history-writing). Ancient writers were more highly selective, ideological, and artistic in narrating the great events of their day or the lives of key individuals. They arranged material thematically as well as chronologically. They included epitomes of key teachings of major rabbis and philosophers. They focused disproportionately on the last days of people's lives and on how they died, believing this to be one of the best indicators of their true character. There are unique features of the Gospels, to be sure, generally related to the unique events they narrate and the distinctive nature of the person of Jesus of Nazareth. But this makes them no less historical or biographical by the conventions of their day. Perhaps it is best, then, to refer to the Gospels as theological biographies?
Loveday Alexander finds the closest parallels to the Gospels, with respect to their genre, in Philo's Life of Moses and in the anonymous Jewish work known as The Lives of the Prophets, both probably written in the first half of the first century. She concludes that this "suggests at the very least that biographical narrative provided a point of cultural contact between Greek and Jew, a flexible and readily comprehensible framework that could be moulded without difficulty to reflect the theology and cultural values of a particular ethical tradition." At the same time, Martin Hengel has insisted that Mark himself may well have applied the name "Gospel" to his document and that, as the other Gospel writers (or their compilers) followed suit, they were not primarily affirming that they were writing works of the same genre nor even that they were composing conventional biographies according to the standards of the day. Rather, in keeping with the meaning of gospel (Gk., euangelion) as "good news," originally used for the message and ministry of Jesus, the label was designed "to bear witness in their works to the one saving message of Jesus Christ."
In any event, what is important to conclude at the end of this two-chapter survey of modern methods of Gospel study is that there is a legitimate place for historical, theological, and literary study of Matthew, Mark, Luke, and John. Despite attempts of various scholars to pit one method against the other two, all three actually go hand in hand. Indeed, unless we approach the Gospels expecting to find historically reliable information, theologically motivated emphases, and delightful literary artistry, we shall overlook important dimensions of the texts and run the risk of misinterpreting them as well.
From Ben Witherington (New Testament History: A Narrative Account, pp 17-24):
When dealing with ancient sources, we cannot be content to know the religious and social settings out of which these sources have come. We should also know something about how the ancients viewed the writing of history and biography, for in the Gospels and Acts apparently we are dealing with three ancient biographies and one two-volume historical monograph (Luke-Acts). What kind of historical information we can extract from these sources will depend to some extent on what kind of data they were trying to deliver and what historical and biographical conventions they were seeking to follow. Thus, a short exposition on these matters is in order here.
The problem of anachronism is a serious one when it comes to evaluating materials in the Bible because there is a widespread assumption in the conservative Christian community, ever since the Reformation, that God's Word requires only a good, clear mind, an open heart, and the guidance of the Holy Spirit to be understood. No particular additional resources (beyond the reader and the text) need be consulted or should intervene.
This assumption lends itself to various forms of anti-intellectualism when it comes to the serious study of the Bible as an ancient historical document. Lacking sensitivity to the ancient conventions about history writing, many contemporary readers assume modern ones to be in play when reading the text. Perhaps the most notorious example of this sort of error is the case of the Christian writer who in a famous book, The Battle for the Bible, concluded that Peter must have denied Jesus six times (something no individual Gospel suggests), because otherwise this writer was unable to account for the varying descriptions of denials and cockcrows in the Gospels. Bringing modern historiographical expectations to the text makes it difficult to appreciate or even recognize the ancient conventions and genre traits that are in play. The modern desire for precision must not be imposed on ancient authors, who often, though not always, preferred to write in a generalizing fashion.
To take another example, the ancients were usually perfectly content to use adverbs and other terms for time in a metaphorical or less-than-precise way. Luke, for instance, is satisfied with saying that Jesus was "about" thirty when he began his ministry (Luke 3:23). This general lack of concern for precision is what makes the more precise time references in the passion narratives stand out all the more distinctly. Up to the passion narratives, Mark's favorite term to indicate the flow of time was "immediately" (euthys), a term the evangelist uses relentlessly, even when often what he means is simply "next." When a modern person tries to press ancient general time notices beyond the general sense the original author was trying to convey, it can only result in distortion.
Furthermore, one could say that the way ancient Jews viewed the day and time was very different from ours. For the New Testament authors, all of whom were Jews (with the possible exception of Luke) the day began at sundown, not at midnight! The whole rhythm of life was different for them. They began the day with a time for worship, or evening fellowship around a table and then rest. It is from the Romans that we have come to reckon the day as beginning at midnight, and we also owe the Romans for the notion that one should get up and go to work at sunrise (this is even when Roman courts began their daily work - cf. the trial of Jesus). Likewise, in regard to the beginning of the year, Jews began their calendar year in the fall, not, as the Romans did, in January. Thus, for Jews the year began with harvest and finished with the summer, a very different way of looking at the cycles of life than we have. This is why Westerners are often confused by biblical phrases like "reaping and sowing" to describe the activities of the year, where they would expect the reverse order of those events.
But it is not just the conceptions of time that differed in antiquity. There were also conceptions about history different from what we find in modern history books, not the least of which is the belief that God was in control of history, orchestrating when certain things happened, especially crucial salvific events. Thus, when we hear the phrase "but when the time had fully come, God sent his Son" (Gal. 4:4), we realize that the apostle would not have subscribed to modern secular notions of either no deity involved in human history or at most a watchmaker God who wound up the universe and then left it to its own devices. To the contrary, it was passionately believed that God intervened repeatedly in human history and indeed was in control of the entire tapestry of events - past, present, and future. This being so, it behooves us to consider closely how ancients dealt with matters biographical and historical.
Let us start with a description of ancient biographies and what their genre traits were, since, I would argue, Matthew, Mark, and John all appear to be such documents, while Luke-Acts appears to be an ancient historical monograph. "The first qualification for judging any piece of workmanship from a corkscrew to a cathedral is to know what it is - what it was intended to do and how it is meant to be used." C.S. Lewis was quite right in this remark, and it is especially apt when it comes to dealing with either an oral presentation or a written document. These sorts of considerations apply especially when the possibility of anachronism is a serious danger, that is, when one is dealing with ancient documents. Works of ancient history or biography should each be judged by their own conventions.
The word "genre" means a literary kind or type. It refers to a sort of compact between author and reader whereby the author, using various literary signals, indicates to the reader what sort of document is being read and how it should be used. The genre signals in the text provide the reader with a guide to the interpretation of the text. To make a genre mistake is to make a category mistake, which skews the reading of the document.
"The genre of a particular work is established by the presence of enough generic motifs in sufficient force to dominate," so that when the reader picks up the document, he or she will know soon thereafter whether to expect to derive from it phone numbers, or definitions of words, or entertainment, or historical or biographical information, or even some combination of such things. It follows from this that it is important to discover what kind of document Mark, or Matthew, or John is.
We must remind ourselves that the possibility of the Gospels being ancient biographies must be assessed on the basis not of modern biographical conventions but of ancient ones.
The one thing to keep in mind is that ancient bioi‚ like modern biographies, center on a particular person and seek to present an adequate and accurate characterization of that person. An ancient biography would include information about other persons and groups of people, but the major focus throughout the work would be on the central character. What was considered revealing of that person's character and personality would be included; what was not so, likely would be left out. Thus, while a biographer might well include a short story or anecdote about a person that was not of any larger "historic" significance, an ancient historian was unlikely to do so.
The aims of the ancient biographer, such as Plutarch, were often hortatory. They sought to inculcate mimesis, positive or negative. The message was "Go and do likewise" (if the biographical subject was virtuous), or in some cases "Go and do otherwise." To be sure, some overlap of features and aims occurred between biography and history, or between biography and moral philosophy, or between biography and encomiums (speeches), but still, the reader could distinguish a life from a tract of moral philosophy. The point is, as Burridge stresses, "Ancient βίος was a flexible genre having strong relationships with history, encomium and rhetoric, moral philosophy and the concern for character."
The historian's concern was with movements, historical developments, cause and effect, synchronisms - that which was historic and epoch making. The ancient biographer also drew on historical data about the central figure, but did so with different aims and purposes. For instance, we should not be surprised that Mark, Matthew, or John seems almost unconcerned about explicating how event A was related to event B, which seems to have followed it. Rather, each of these evangelists sought to ask and answer this question: Who was Jesus, what was he like, and why is he worth writing a biography about?
In evaluating Mark, Matthew, and John as biography, we must have a firm handle on these Gospels' chronological and social settings, broadly speaking. Whatever their precise dates, Mark, Matthew, and John were written after the beginning of the Roman Empire and during the period of the rise of the Roman biographical tradition, following in the footsteps of the Greek biographical tradition. What the Roman tradition added to the discussion was a greater concern for family traditions, the need for the demonstration of public honor, and, sometimes in the latter two-thirds of the first century, a focus on the hero's patient suffering and death under a tyrant (see, e.g., Thrasea Paetus's Life of Cato). "The genre oiexitns illustriutn virorum became fashionable under oppression by Tiberius, Nero, and Domitian. Such a focus on the subject's death [often an untimely death] is an important parallel for the Passion narratives in the gospels."
Each of these three Gospels has been called a passion narrative with a long introduction. These Gospels have this form partly because they were written in an environment where there would be a certain sympathy in the empire for the chronicling of a life that could be shown to be a good or virtuous life that unfortunately suffered an untimely and unjust end at the hands of some authority figures. In fact, Mark devotes some 19 percent of his narrative to the passion narrative compared to 15 percent by Matthew or Luke - proportionally more emphasis in Mark on the last week of Jesus' life than in the other Synoptics. John's Gospel, however, places even heavier emphasis on the last week of Jesus' life, beginning in chap. 12 and continuing until chap. 20 (the whole second half of the Gospel).
A variety of external and internal features of these Gospels points us in the direction of biography of some sort. First, they are the right length (Mark has 11,242 words, Matthew 18,305, John 16,150). Matthew actually is at the upper limits for a biography (Luke at 19,428 being at the upper limits for what a single scroll could contain), but Mark is closely similar to the average length of one of Plutarch's Lives. Second, these works, even at a glance, clearly are continuous prose narratives, which places them in the category of history, biography, or romance. These Gospels clearly are not moral tracts, speeches (encomiums), or even plays, though John is more like a drama than the other two Gospels in question. Mark and Matthew have a basic chronological and even geographical progression - from a largely northern ministry to a final visit to Jerusalem, from Galilee to Jerusalem. Third, notice how rarely Jesus is not the center of attention of any given narrative. Take, for instance, Mark's Gospel (an exception would be the story about Herod in chap. 6, but even there Jesus is discussed at 6:14-16). Jesus or his teaching is the subject of over 44 percent of all the verbs in Mark's Gospel, and in almost any given narrative, Jesus is either the center of attention or discussion, or not far from the spotlight. These books are the good news about Jesus, and they seldom stray any distance or length of time from their main subject.
Fourth, each of these Gospels follows the ancient biographical convention of using indirect portraiture to reveal the central figure. By this I mean that the evangelist largely lets Jesus' words and deeds speak for themselves. He does not intrude upon the story with a great deal of authorial commentary, nor do we find much first-person commentary by Jesus about himself. Fifth, Mark and Matthew are characterized by the use of short anecdotal stories that focus on a word or deed of Jesus, and whether we call these pronouncement stories or, more appropriately, chreiai, the stringing together of these condensed narratives was indeed characteristic of ancient biographies. Here John differs, but it can be seen as more of a philosophical biography, dealing with dialogues and monologues involving the one who is the Word on earth.
Sixth, the usual subjects for ancient biography were public figures such as emperors and generals, or literary figures such as rhetoricians and poets, or sages and philosophers. Bryan suggests that an outsider reading Mark, even more so Matthew, likely would assume that the work was a biography about some sage. This is equally true of John. It was not unexpected that sages would be misunderstood and suffer at the hands of society, being treated as the nonconformist outcasts that they often managed to be (see Lucian‚ Demonax 11.65). Finally, in regard to Mark's somewhat rough Greek or John's somewhat simplistic style, it must be borne in mind that bioi in the first century A.D. were by nature popular literature. They did not need to be seen as being in the same league as Virgil's Aeneid or Homer's Odyssey, or being as precise as a careful work of history like Thucydides' History. The goal was to create a lasting impression through the impact of the whole bios.
One would not expect of an ancient biography a "womb to tomb" chronicling of a person's life. Nor would one expect much time or focus on the early childhood development of the person in question, since it was believed that character was basically static and did not develop over time, but rather, was merely revealed. The author would not necessarily be concerned to recount even all the historic events that transpired in the main character's life, since the goal was to reveal who this person truly was, through a portrait of words and deeds, not to give an exhaustive life account. A representative sampling of a person's life activities that revealed character would be more than sufficient. Finally, if the person's death took place in some glorious or inglorious fashion, ample space had to be devoted to explaining the significance of the event because it was widely believed in antiquity that how one died revealed one's true character and, more importantly, what God or the gods (in a pagan biography) thought about that person. Needless to say, since Jesus was crucified and no one in antiquity saw this as a noble way to die, much explaining was required of Matthew, Mark, and John if their hero figure was to be viewed sympathetically by a first-century recipient of one of their Gospels. Judged by ancient standards then, Matthew, Mark, and John all look rather clearly like ancient biographies of the more religious or philosophical sort.
(NB: I don't necessarily agree with everything quoted above, but there's some useful information.)