What rational thought? The only thing Gag showed there is that he's never even read it. For starters, it's not 4,000 years, it's 6,000 years. And the Bible never says it, not once. The idea was proposed by James Ussher, an Anglican Archbishop in the 17th century (which is why it's commonly called the Ussher Chronology). It's never been commonly accepted by religious scholars, and the only reason people know about it so much in America is because it used to be included with every KJV Bible, as that was the official translation of the Anglican church, and the most common text in most American Protestant denominations up until a few decades ago.
Call the Bible what you want, but at least read it or study it just once in your life if your going to exert so much effort into hating it. It might help prevent you from looking even stupider than the Fundies do.