Prof. Enns' book uses the word in this way: "an ancient, premodern, prescientific way of addressing questions of ultimate origins and meaning in the form of stories: Who are we? Where do we come from?" (50) That is to say, if I may be so bold as to paraphrase Prof. Enns, narratives which demonstrate truth as art but not necessarily as empirical truth.
At any rate, this word "myth" is an interesting one. Somehow saying that the Bible contains "myths" and therefore we have some liberty or obligation (depending on how the argument is being phrased) to read it less-rigidly than we would a history book or newspaper apparently makes one's hermeneutical approach better. For example, Prof. Enns uses this word (as I have read in John Armstrong's counter-review of the work) not to denigrate Scripture but the patch up the home-job Evangelicals and Protestants have made over the years in reading the interpretations of the OT made by the NT.
This criticism/approach comes from the neighborhood in which "modernity" and Enlightenment epistemology are seen (by some) as the low-point of intellectual wrestling in the West or (by others) as a rigid filter which is incompatible with the worldview and epistemology of the culture(s) in which the Bible was written, causing those who are stuck in "modernity" to miss the point of ancient texts pretty significantly.
To those in that neighborhood who have stumbled onto this blog, I say, "welcome to the other side of the tracks."
One of the major assumptions of your criticism ("you" being those critical of "enlightenment" mojo) is that Peter, Paul and the other fellows writing the NT didn't view text the way an Enlightenment reader would view text. If you're going to try to make me answer yes or no to the question, "Did Peter, Paul and the other fellows writing the NT view text the way an Enlightenment reader would view text?", I admit I'd have to answer "no". But their view of text was not as loose as your critical opinion demands, either.
Now: how do I come to that conclusion? It comes back to that little word "myth" – a word we can find in the NT 5 times.
Now here's my theory: if we can determine what the writers of these verses meant in context by using the word "muthos", we can have some insight into their view of the epistemology of language and their view of how to handle texts.
We're going to look at each passage individually, then take a look at the cumulative effect at the end. It is my (yet to be substantiated) thesis that the way Paul and Peter use this word in these passages undercuts the view of "myth" being proposed actively by some quarters today.