Tim Keller Answers a Question regarding the Literal Adam

Tim Keller does a Q & A, answering the question regarding the histrocity of Adam at the Gospel Coalition blog. 

I find this blog post interesting.  I deeply respect Tim Keller and his effectiveness in communicating Biblical truth.  I found much of his arguments sound, resonating with the idea of upholding the inerrancy and inspiration of God's Word.  He essentially argued that Genesis 2-11 needs to be understood as events that had actually happened.  With regard to Adam, he succintly tied the idea of federalism of Romans 5 with the understanding of Adam being an historical person.

Sadly, Dr. Keller arguing for the literal Adam because the author of Genesis 2 conveys this, states the following,

"I don’t think the author of Genesis 1 wants us to take the “days” literally."

Within the very paragraph he makes the statement above, Dr. Keller argues that Paul desires for his readers to understand that he takes Adam and Eve literally and therefore we must take it literally.  He closes the paragraph stating,

"When you refuse to take a biblical author literally when he clearly wants you to do so, you have moved away from the traditional understanding of biblical authority."

The question that is being begged is, "If the author did not want us to take the six days literally in Genesis 1, how are we to understand the same author when he refrences back to Genesis 1 in Exodus 20:11?"  If Tim Keller rightly argues that we are to take Paul's understanding are we not to take Moses' understanding as well?  For Dr. Keller to hold to his belief on Genesis 1, he would need to argue that Moses was arguing for the need of the literal Sabbath based on a figurative one.  He correctly disproves such an argument from those who question the histrocity of Adam and yet is willing to overlook a more historical understanding of Genesis 1 from Exodus 20.