In that case, why not simply refer to them as "Judeo" values since nothing about them is distinct to Christianity?
I can't say that America is a Jewish nation, or one founded on Old Testament principles. That would not be accurate since it would include many things on which Jews and Christians disagree. I do believe America was founded on a common core of Judeo-Christian principles, with deliberate and intentional decisions made to include people who would not have been part of the acceptable consensus of churchmen and dissenters in contemporary Britain, such as Roman Catholics and Jews. While “freethinkers” such as Jefferson and Franklin were certainly part of the mix, they shared what in those days was considered a common moral consensus and were a pretty small minority.
Got to go...