Woot, I was hoping you'd bite on that.
Incidentally, allow me to clarify something: I don't take these sorts of debates all that seriously. I just enjoy them when they happen, because I happen to enjoy debating over the "big topics". It's fun. Had I been born in a different time, I think I might have enjoyed being a theologian.
But anyway.
There is a difference between the parables, which use a hypothetical or sometimes real situation to illustrate a moral lesson, and the myths, which use the supernatural to explain something that the author does not understand.
God created the Earth in seven days is an example of a myth. It explains the origin of the earth (something anybody really has to be curious about) with a supernatural power (God did it).
The Prodigal Son is a parable, and the difference between the two is fairly obvious.
For those who decline to believe the Bible word for word, which is pretty much most of what is arguably considered Christianity these days, I might add, the question becomes how
much of the Bible they're willing to disregard.
Creationists are considered somewhat unusual because they actually
believe the creation myth, after all.
But really, the concept of God creating the Earth in 7 days is no more unbelievable than Moses parting the Red Sea, or Jesus walking on water.