Different Christians believe different things. I would venture to say that if the Bible and a scientific fact ever appear to contradict each other, it's that we're understanding the Bible wrong. Not that the Bible itself is wrong, but things can be misinterpreted.
My own belief is that some parts of the Bible are literal, while all of it is true, and that "true" and "literal" don't have to mean the same thing. For example, when Jesus called the Pharisees "snakes" and King Herod a "fox," He was obviously using figurative language. The Pharisees were not really legless reptiles, and King Herod was not actually any of several species of the canid family. So, sometimes the Bible can use figurative or symbolic language and still be true.
The Creation stories, then, I would say can be open to a number of explanations. It's possible God did everything in six literal 24-hour days, and somehow made it appear otherwise. He's powerful enough to do that, and we don't always understand His ways. It's also possible, based on other passages in the Bible, that "day" doesn't necessarily mean a period of 24 hours. We don't always mean it that way ourselves, such as when we say, "Back in my day, things were like this or that." We don't mean 24 hours. We mean an indefinite period of time, but we say "day."
And that's just my opinion.
I saw on our Mass-sheet today a very brief little piece, with the following comments in conclusion :
'It is not necessary for us to understand either the garden of Eden story or Jesus' experience with Satan as being historical. These stories are primarily vehicles to communicate important stories to us.'
The final sentence clearly makes sense. Sola Scriptural types often have a greatly impoverished understanding of the nature of scripture, since they read it in an entirely linear way, failing to realise the profound truth of the saying that God draws straight with crooked lines. In other words, our attitude of humility, when we read the scriptures must subordinate our reading of the text as a starightforward exercise in English comprehension to the certainty that what is being conveyed is, in fact, a supernatutal and therefore extremely mysterious nature, increasingly involving paradoxes, mysteries of the faith, the more profoundly we penetrate the meanings and messages contained in the various texts.
Perhaps the most classic example of this is the text, in which it is related that many peple then stooped folloiwing Jesus, i.e. the passage in which tells his siteners that they must eat his body and drink his blood.
The problem with the brief passage I quoted above is that a similar-seeming mindset has, in the past, led to a modern form of gnosticism, and one might say equally argue that it is even less necessary to understand either the Garden of Eden story of Jesus' experience with Satan as being
unhistorical.
If, as the author truthfully indicated, is is not necessary to view the story as literally true, that will surely lead to the more worldly intellectuals among the scripture-scholars and theologians to entertain an ever-growing scepticism that takes us 'right off the reservation'. I did hear an elderly seminary lecturer tell our class that, of course, God wouldn't have really walked in the Garden of Eden...
Well, now, whatever the ostensible dubieties concerning the literal truth of, for instance, the snake's talking to Eve, there is surely nothing too fanciful about a god who was prepared to be incarnated as a tiny, mortal human-being deigning to walk in the Garden of Eden - presumably assuming a human form, as was the wont of the angels - as Almighy God. That assumption that God would be far too grand to bother about us piffling little mortals to the extent of interacting with individuals, is a common belief of athiests, who show a surprising knowledge (at least, claimed as such) of how Good would or wouldn't act.
So, it is easy to see, rather, that it would only serve as the 'thin edge of the wedge' for many of the more academically-trained Christians, to needlessly dismiss the historicity of other Bible stories, since they have proved so gullible in the matter of science. Their understanding of the philosophy of science, most notably the implications of quantum physics, and now
information as the basis of all living things, they have simply had to accept them, wholesale, without being able top offer anything but thoroughly risible, materialist conjectures by way of explanation.
Note that one the putatively basic scientific axioms is said by the OP to be that the earth is 13 1/2 billion years old. Well, it happens that an atheist believer in the latter admitted, as if jokingly, that one of the implications of quantum machanics is that the world we see at any moment migh be very much less than a nano-second old. I believe that is to do with the fact, again, well empirically attested, that when we cease to look at a thing, it ceases to exist. The implications eesmms to be that we each were born, live and die in a little world of our own, integrated and coordinated by an omniscient and omipotent agent (clearly, God).
That, in turn makes it far easier to understand how even such a god could be the agent behind light-beams that tracks every human Observer, whether stationary or traveling at a constant speed, at their own absolute speed.
The idea that science is somehow the standard against which all truth must be measured is actually a very sorry joke. Your opinion sounds 'on the money' to me, LovebirdsFlying.
We are glad that you've joined us. 
