The biblical descriptions of creation and the flood are ancient texts that address ancient issues within the scope of ancient ways of knowing. These stories are not to be read as if overlapping with or informing scientific investigation of human origins or modern notions of historiography. To think that they do is a genre misidentification of a most fundamental order.
But there is something more important than just excluding certain genre options. Calibrating the genre of Genesis by ancient standards will lead to positive articulations of the nature of Genesis that also respect its ancient setting. In the Genesis/science dialogue, it is not enough to say “we know that Genesis is not science” and be done with it. We must also attempt to articulate, in as direct and unflinching manner as possible, what Genesis is. What was the book of Genesis written to do?
Addressing this question will help us articulate positively how Genesis contributes to Christian thought. The synthesis of Christianity and evolution is all too often perceived as taking something away from Genesis (its literal, historical, scientific value) and leaving nothing behind. Rather, a comparative approach will leave us with a proper notion of what Genesis contributed to ancient Israelite thought, what it now contributes to Christian thought, and the extent to which that entire dynamic can be brought into the Christianity/evolution discussion.
Peter Enns at BeliefNet.com