Any study of a book of the Bible must begin by addressing the issue of Genre. One of the most elusive aspects of Mark, and indeed of the Gospels in general, is identifying and assigning to them a specific genre by which they might be best interpreted. Many suggestions have been set forward, including the idea that the genre of Gospel (εὐαγγελίον) was a new, independent invention by the gospel writers. Aside from this idea, however, most of the theories regarding the genre of the Gospels – and Mark in particular – place it somewhere in the realm of biography or narrative history, with the former being the most common.
One of the greater objections to considering the Gospel of Mark to be a biography is that the author has no intention of including a history of Jesus’ birth, childhood, or early adulthood. These aspects appear to be important as per the definition presented by David Aune, that “biography may be defined as a discrete prose narrative devoted exclusively to the portrayal of the whole life of a particular individual perceived as historical” (though he places Mark as a sub-genre of Greco-Roman biography). According to Collins, Vielhauer concluded as well that “Mark is not an example of a Greco-Roman ‘life’ because, unlike the typical ancient biography, it shows no interest in the origins, education, and inner development of Jesus.” So on these two counts (and more), the Gospel of Mark does not appear at first glance to be a simple biography written in the same mode as traditional Greco-Roman biography.
However, many advancements have been made in the comparison of the Gospel accounts with variations of biographies in antiquity, resulting in a broader definition and structure of biography. Burridge took this opportunity to reinterpret Greco-Roman ‘biography’ as βιος, rather than biography, granting more flexibility to this ancient genre. With this reinvention or expansion of possibilities of this genre, one finds many examples which would allow for a more forgiving understanding of biography, one that would allow Mark to be classified as such. Many have therefore begun to understand Mark as a “historical biography,” βιος, or even an “apocalyptic historical monograph” (so Collins).
It is a point of interest, however, that without these elements of early biographical material, Mark has famously been described as a “Passion narrative with an extended introduction.” This description is telling, for it recognizes the purpose of the work as primarily theological, as it is focused on Jesus’ Passion and resurrection, with these things, themselves, being instrumental to the implementation of the Kingdom of God. Mark (as is evidenced not only throughout the book or at its end, but in its very prologue) is theological in nature, with the narrative serving the purpose of 1) establishing the events in a historical context, and 2) driving the story along to reach its theological conclusion. Vielhauer believed the motivation for the writing of this gospel to be based in the crucifixion and resurrection of Christ, which we see evidenced through Mark’s special attention to the last week and even more so to the last hours of Christ’s life, as time slows steadily at that point (a rather deft literary device to draw attention the emphasis of the work).
Taking these things into account, then, and with purpose and genre being inseparable, I would argue that Mark’s purpose was to assemble his received material in a way that displayed a particular theological point that he wanted to convey. Mark, therefore, is a collection of events of the life of Jesus constructed around a theological purpose. And so, answering the original question, I would not classify the Gospel of Mark so much as a “life” of Jesus, but as a “theological biography,” for the author’s intent is clearly theological, and at the center of this theology is the person of Jesus Christ. It is truly so much more than the life of a man, but includes what theological and eschatological implications were brought into the realm of humankind through the life of Jesus of Nazareth while constantly challenging his audience to wrestle – alongside the characters in the story – with the identity of who this man really is and with what authority He has to institute this sort of divine kingdom among men.
 David E. Aune, The New Testament in Its Literary Environment (Cambridge: James Clarke & Co, 1988), 29.
 Ibid, 46-76.
 Adela Yarbro Collins, Is Mark’s Gospel a life of Jesus? (Milwaukee, WI: Marquette University Press, 1990), 10. Vielhauer also held the view that “the gospel form itself is something new” (ibid).
 Richard A. Burridge, What Are the Gospels? A Comparison with Greco-Roman Biography. (Grand Rapids, MI: William B. Eerdmans Publishing Company, 2004), 233-255.
 Martin Kähler, The So-Called Historical Jesus and the Historic, Biblical Christ, trans. C. E. Braaten (Philadelphia, PA: Fortress Press, 1964), 80.
 Philipp Vielhauer, Geschichte der urchristlichen Literature (New York, NY: de Gruyter, 1975), 350.