All doctrines which rely upon ancient authority are doomed to obsolescence.
As an example, one of the most important advantages that a scientific outlook has over a religion-based one is its ability to admit it was wrong; that is, science has the ability to self-correct over time.* A venerable, successful religious tradition may have the weight of centuries behind it to speak in its favor; but that weight simultaneously forever hinders it, keeping it chained or rooted, as it were, in one spot. New scientific discoveries, however, can upset essentially any scientific knowledge that had preceded them, as long as the new theories and frameworks are compelling enough. It's hardly an overnight process--see the 20th century's resistance to quantum mechanics as an example--but science can "afford" to throw out anything as long as it has a suitable, stronger replacement. (It tends to be a further requirement that new discoveries explain old observations and show why old theoretical laws worked, of course.) Christianity, by contrast, cannot afford to throw out the belief that Jesus Christ was God's son, that he spoke God's words, that God's words are trustworthy, that our present texts are accurate reproductions of the originals, and all that. If one removes Christ from Christianity, the belief system reverts to Judaism. (Probably, that is; I'm sure this oversimplifies matters, but I think that's okay for my purposes. On the other hand, if they're fine leaving a large chunk of things unexplained, Christians could probably throw out most of the Old Testament without a problem; I personally suspect they'd be better off if they did so, but that's a discussion for another time.)
However, religious views don't have to be static, in a sense. Thanks to the exquisitely ambiguous nature of language and humanity's marvelous propensity for inventing alternative explanations, a faith's interpretations may change, while their holy sources remain unchanged. As science continues to undermine religious claims, this will more and more become the refuge of believers--that is, unless the public at large continues to ignore scientific knowledge whenever and wherever it pleases. As evolution attains greater and greater acceptance, Judeo-Christians turn toward interpreting Genesis in some kind of metaphoric or allegorical sense. (The future may yet hold some revision for the specifics of evolution, maybe even a somewhat drastic reconceptualization of it; but at the least, I'm very confident that there is no way a literal reading of the story of Creation can be true. Even if evolution is somehow radically undermined, it will be replaced by a theory very similar to it, and regardless, this theory will never accord with Genesis in a literal way.)
This illustrates the necessity of fluidity and open-mindedness in a world-view, even where non-scientific projects are concerned.** Science, philosophy, and flexible religious interpretations have the advantage over immutable fundamentalist faith because, well, all human knowledge is pretty fragile and subject to revision.‡ The times they are a-changin', and blind, continual adherence to any systems or traditions means being left in the dust.
This post isn't about religion, really; it's about one's ability and willingness to adapt to that which is new and unfamiliar. Faith's resistance to scientific (and social/moral, for that matter) developments is only a conspicuous example of failing to do so that's been strung out through history. In this post, I don't think I've covered very well just why adapting to new changes is desirable, but I hope that's intuitively obvious/self-evident to the reader.
The lesson to take away from this is a reminder not to get stuck in your ways, especially as the rate of social and technological change accelerates in today's world. This comic, though humorous, points out what could be a genuinely serious issue, as medical science extends the human lifespan.
Zach Weiner's "Saturday Morning Breakfast Cereal", #2184. Transcript:
NARRATOR: Good thing: someday, longevity will be discovered.
MAN: I'm gonna live forever!
NARRATOR: Bad thing: imagine having to deal with an ancestor from the 13th century.
13TH CENTURY MAN, TO IRRITATED MODERN WOMAN: We need to put a sticker in every astronomy text! The Copernican view is just a theory!
NARRATOR: Good thing: if it's discovered in your lifetime, you get to be the crazy ancestor.
FUTURISTIC MAN W/ WIFE: Great Great Great Great Great Great Great Great Grandpa! Stop using your ultraglasses to stare at my wife's boobs!
OLD MAN W/ FUTURISTIC GLASSES: That's how we did in the 21st century and I'm too old to change!
It is a sad fact that change happens most quickly and easily when an older generation dies out, and a newer generations's views become dominant. I think we want to avoid the "old racist/sexist/homophobe syndrome" at all costs; so it will be imperative that, if we do ever extend the human lifespan to much longer lengths, we do so with a society (a species, really) that is willing to be flexible and to adapt. (A global, or even nation-wide, shift in human thought is far too optimistic to hope for in reality, unfortunately, but we should strive toward that ideal nonetheless.)
Finally, let me supply a quote from Charles S. Peirce (I forget from where, exactly: it's in one of the Collected Papers):
* Forgive me for encouraging unnecessary dichotomies by pitting a "scientific" mindset against a "religious" one as though they were mutually exclusive, but I'm talking specifically about religious views that look to ancient texts and doctrines as sources of unchanging truth, in defiance of modern scientific discoveries.
** It amuses me that I follow dogmatic tendentious assertions about the falsity of Genesis with urgings toward "fluid" and "open minded" beliefs. There's some tension here: I will admit, yeah, it's possible something new could shake that ardent disbelief of mine. I just believe that possibility so unlikely as to be not worth discussing or considering as a serious option.
‡ Mathematical and logical truths may be an exception, but we must keep in mind that we can still be wrong about those truths due to misunderstanding them. At least, the more complicated ones. Furthermore, I'm sort of a formalist/constructivist hybrid, and I think that logical and mathematical necessity is necessary simply because we define it that way, except perhaps at the barest level. (Is it possible for a thing to not be itself? No, that's merely playing a game with semantics. I don't think all philosophical problems can be explained as nonsense-disguised-as-something-intelligible a la early Wittgenstein and the positivists; but for the most fundamental of logical questions, I do.)