Perhaps someone can enlighten me but unless you interpret the Bible literally, there is no validation to anything in the text. The Bible is supposed to be a historical relic, depicting various trials and tribulations of men and angels alike, and the possibilities of our foreseeable future. Unless we interpret this literally, all the Bible is are metaphors, memes and themes that were written in order to inspire and preach a certain moral code.
If I read that Moses heard the voice of God through a Burning Bush, I am not seeing that as an accurate testament to something that REALLY happened. I am seeing that as something symbolic and metaphoric. An allegory if you will. And THAT is where the argument comes from. You cannot argue half and half. You cannot take the middle road with the Bible. You cannot claim that some of it is metaphor, some of it is fact, some of it is this or that, because, honestly, who are you or who is anyone else on this planet to truly know how to interpret this book with any kind of accuracy? The only glimpse of an idea we have on how to read it, is in the book itself, which requires a literal interpretation.
It is all confusing and contradicting. Everything associated with religion in general only leads to a giant circular, never-ending argument.
In short, you cannot say the bible is as factually solid as 2+2=4, and then say, except for this that and the other thing.