And why, pray tell, would the people who wrote down the bible use the word "day" when they really meant "millions of years"?
This kind of "re-explanation" of the bible has been going on for hundreds of years now. It used to be that the 6 days of genesis really were 6 days. It used to be that stoning the unbelievers was the thing to do. Advances in science and changes in society have chipped away at the bible little by little. In the end, there will be nothing left.