I've given it some thought. Religion, as presented through any holy text, interprets the universe in a similar manner that comic books also present their own universes.
I think arguing within the context of a particular religion is only valid within the universe created by theologians (or religion's authors), not outside in the real world. If I try to say something that is contrary to or alien to what is understood by Christians, for example, it isn't really understood and/or I am corrected by a restatement of that religion. For instance, I might say that there are contradictions in the Bible. The response would be, "Well, you gotta look at the context of the whole thing."
It's kind of like people that study Dungeons and Dragons, Star Trek or Star Wars. If I asked "If Anakin Skywalker, or even Luke Skywalker, were supposed to bring balance to the force, why is it that they only left it either in darkness (Episode 3) or in light (Episode 6), instead of there being an actual balance?"
The reply I'll get when I actually ask this question might be, "If you would've read the books that go along with the Star Wars series, you would've seen that it was actually the son of Leia and Han Solo that would bring balance to the force." Wow! And apparently, this is true, and that's what I mean. Religion is kind of like a comic book or an alternate universe that was created by people, and then others get into it and contribute more to it.
Sooner or later, the people in charge (or the original storywriters) have to authorize certain people who can contribute to the universe (this is what George Lucas did with a few authors of Star Wars books, this is what the Pope had to do when the Catholic Church had to choose which books to keep in the New Testament, and which to throw out).
Anyhow, the difference between religion or a comic book universe is that the barrier that we have to distinguish fiction from reality isn't there anymore. These religions were created so long ago, during a time in which people really were able to believe these things, that of course stories like the Flood were widely accepted then.
Today, however, we have scientific evidence to deter any new religions (though maybe not cults) from appearing again, but we're still stuck with the same old ones. Why? Because they predate modern scientific methods. And because these religion predate modern scientific methods, we are left with the lingering doubt of each religion: "What if they are true?"