The relationship and dependence of the early chapters of Genesis on ancient Near Eastern myth raise the question of whether these chapters can themselves be designated as myths. The problem is compounded by the controversial issue of the definition of myth.
--John S. Kselman, HarperCollins Bible Commentary, p. 84
But if that which tends to make us happier and better can be called useful, then we claim that epithet for [mythology]. For Mythology is the handmaid of literature; and literature is one of the best allies of virtue and promoters of of happiness.
--Thomas Bulfinch, Bulfinch's Mythology, preface
A concerned reader writes,
I note that one of your interests seems to be the use of myth and mythology in fiction and popular culture. Here's a question I'd like to see you address and invite your other regular readers to weigh in on. The question is: Can a Christian author appropriate elements of a pagan mythology for narrative and dramatic purposes without appearing to endorse that mythology? If so how? Admittedly these questions are broad, and there is no definite answer, but I would be interested to see what you and your readers think.
The answer to the first question is yes, and I say this because Christians and Jews have been doing it for a very long time. The most important scriptural passage related to the subject is Genesis 6.1-2,4:
When people began to multiply on the face of the ground, and daughters were born to them, the sons of God saw that they were fair; and they took wives for themselves of all that they chose.... The Nephilim were on the earth in those days--and also afterward--when the sons of God went in to the daughters of men, who bore children to them. These were the heroes that were of old, men of renown. [NRSV, with emendations]
I know of three interpretations for this passage. Early Church Fathers such as St. Justin Martyr and Tertullian, following a text then popular, the Book of Enoch, understand these sons of God to be fallen angels whose congress with human women produced a race of giants. Enoch depicts these giants later transforming into injurious spirits, which St. Justin takes to be Satan and his demons.
Later, when this interpretation and the Book of Enoch both fell out of favor, Church Fathers generally explained the passage by claiming that the "sons of God" were actually the Sethites, that the "daughters of men" were Cainites, and that the mixing of the two lines led to an increase of immorality, though why these immoral offspring should be "men of renown," I do not know.
The first interpretation stands at the end of a long and colorful line of mythological development that has probably masked the Genesis author's real intention, but the passage in question does not really allow the second interpretation, which I consider a means of explaining the text away rather than of explaining it. A third interpretation, which I arrived at independently, but which you can find in the footnotes of the NAB and probably in some other places, is hinted at by the tantalizing fragments in The Dead Sea Scrolls of a text sometimes dubbed the Book of the Giants. In this book, which is similar to the Book of Enoch, one of the Nephilim is named Gilgamesh.
The passage itself actually tells us what it means. If we ask, "Who are the Nephilim?", Genesis 6.4 answers, they are "the heroes of old, the men of renown." In other words, you already know them. You are familiar with their stories. They are the half-man, half-god heroes who walked the world in days of yore. They have names like Heracles, Achilles, Gilgamesh, and the like. Within the mythological primordial history of Genesis, in these few short sentences of chapter 6, the author gives place to the great stories with which his readers would have been familiar. He makes room for the pagan myths.
Other passages throughout scripture evidence the heavy influence of the Near East's shared mythology on the biblical writers. Perhaps one of the best examples is in Isaiah 14.12ff. In this passage, Isaiah calls the king of Babylon "Day Star, son of the Dawn" (NRSV), and describes him trying to ascend to the very throne of God on Mount Zaphon (not, interestingly, Mount Zion), but failing in his endeavor and being cast down into Sheol. Isaiah is here drawing from Canaanite mythology: when Baal the Thunderer, whose throne was on Mount Zaphon, was swallowed up by the god of death, Mot, then the god of the morning star, Athtar the Awesome, attempted to ascend to his throne and take his place. However, Athtar discovered that his feet did not reach the footstool and his head did not reach the headrest, and he realized he could not take the place of Baal the Thunderer, so he instead became a god of the underworld (cf. Coogan's Stories from Ancient Canaan, p. 116). Clearly, Isaiah here is unafraid to use pagan myths to get his point across.
In doing this, Isaiah is only doing what many Christian writers, and others, would do after him. Thomas Bulfinch, who produced the classic Bulfinch's Mythology, writes in his preface,
Without a knowledge of mythology much of the elegant literature of our own language cannot be understood and appreciated. When Byron calls Rome "the Niobe of the nations" or says of Venice, "She looks a Sea-Cybele fresh from ocean," he calls up to the mind of one familiar with our subject, illustrations more vivid and striking than the pencil could furnish, but which are lost on the reader ignorant of mythology. Milton abounds in similar allusions. The short poem "Comus" contains more than thirty such, and the ode "on the Morning of the Nativity" half as many. Through "Paradise Lost" they are scattered profusely. This is one reason why we often hear persons by no means illiterate say they cannot enjoy Milton.
Then of course there is Beowulf, which is, more or less, a Christian telling of a pagan myth, or the Heliand, which is, so I understand, a Christian mythologizing of the Gospels. Nor can we forget the Arthurian legends, a complex stew of Christian and pagan-derived elements. And what shall we say of Dante's Divine Comedy, in which he pictures Hell peopled with historical and mythological figures side by side, all in a world drawn from the Aenid? Dante takes all the myths at hand and, like the aforementioned author of Genesis, places them under the umbrella of monotheism.
There are more recent Christian authors as well who make heavy use of myths:
The Atlantis story also comes to us from antiquity, through the Greek philosopher and mythopoet Plato, who grew up under the spell of Homer's epics as well. Thus Tolkien also comes under the spell, connecting his Middle-earth Legenderium to the Greek myth of Atlantis; when he wrote The Lord of the Rings, he identified it as the story of the inhabitants of Middle-earth after the fall of the kingdom of Númenor, a rough parallel to Atlantis. Though Lewis is perhaps most famous for his Narnia stories [which also use pagan mythology], his favorite of his own works was Till We Have Faces, a retelling of the Cupid and Psyche myth. His source for that was Apuleius's Latin classic The Golden Ass. [Dickerson and O'Hara, From Homer to Harry Potter, pp. 94-95]
Instead of asking if Christians ought to use myths, we should ask instead why there would be any reason they ought to stop. I can think of none.
As for the second question, regarding how to use mythology, the answer is another question: how do you want to use it? You can use it through metaphor or through the appropriation--or subversion--of mythological characters, settings, and artifacts, or even by making up your own mythology, drawing on existing ones. If you're concerned with creating an explicitly Christian sub-universe, you can always do what Dante and Tolkien did and settle everything under a monotheistic umbrella, which you will find is a broad umbrella indeed. You may even have reason, if it better suits your story, not to mention monotheism, as Tolkien usually didn't. I am currently designing three works, one of which takes place in a universe ruled by 32 gods, 12 of which incarnate from time to time, another in which the closest thing to a god is a collective of superintelligent bacteria that produces avatars by infecting people and rearranging their DNA, and another in which all the myths and legends I can get my hands on are jammed together and syncretized within a decidedly Christian universe. The people who would be offended by this sort of thing aren't in your target audience anyway: because you only live inside your own head and not inside other people's, you can only write for your own tastes, so your target audience is people who share your tastes. The sort of legalists who get offended by the content of fantasy novels (but read them anyway) and then write books about how offended they are cannot possibly be the target audience for a fantasist.
I do not make this last remark facetiously. I realize that allowances must be made for differences in taste and life experience, but we seem to have reached a time in which a great many Christians are suspicious of mythology and its less dignified (due to lack of age) younger brother, fantasy. This attitude of suspicion and tendency to interpret stories in the worst possible light is a reaction--an unhealthy reaction--to a perceived increasing hostility toward (or at least lessening patience with) Christianity in the culture at large. To cure this disposition of suspicion regarding fantasy, we should first relax and remember that we are talking about fiction, and second, we should remember that literary works are generally open to more than one interpretation. After remembering those two things, we will be better able to approach fantasy works fairly. As for mythology, we must only remember that we really have nothing to fear from it, because the pagans became Christians and now their myths are ours. It isn't only Padmasambhava who can contend with deities and transform them into guardians of the dharma; our missionaries, too, are god-wrestlers--we turn deities into saints.
And that dismal cry rose slowly
And sank slowly through the air,
Full of spirit's melancholy
And eternity's despair;
And they heard the words it said,—
“Pan is dead! great Pan is dead!
Pan, Pan is dead!”
Gods who die sometimes refuse to stay dead, but when they rise, they may rise as Christians. Pan still plays his pipes, and his train still follows, but the tune he plays is "Ave Maria."