Obama asks "Which scriptures should guide our policy?"

From Sarah Pulliam:

Obama also cited the Sermon on the Mount in his June 28, 2006, 'Call to Renewal' address.

"Which passages of Scripture should guide our public policy? Should we go with Leviticus, which suggests slavery is ok and that eating shellfish is abomination? How about Deuteronomy, which suggests stoning your child if he strays from the faith? Or should we just stick to the Sermon on the Mount - a passage that is so radical that it's doubtful that our own Defense Department would survive its application? So before we get carried away, let's read our bibles. Folks haven't been reading their bibles."

Well, which passages of Scripture should guide a christian doing a job, any job? I'd start with this one.

The President's job description is stated in the oath of office:

I do solemnly swear (or affirm) that I will faithfully execute the office of President of the United States, and will to the best of my ability, preserve, protect, and defend the Constitution of the United States.

I don't think the scriptures have much to do with the job description or the measurement of how well the job is being done. There's ways of amending the Constitution to adopt or reject similar principles from scripture. Am I missing something important here?