1. I don't know what the original intent of the framers of the U.S. Constitution was in regard to this particular issue. There may be something one could find in the Federalist Papers or some other personal documents written by them that might substantiate your view.

2. Methinks that the majority of the framers of the U.S. Constitution were not Christians according to a biblical definition. However, it would appear that some/many held to Judeo-Christian ethics. But I doubt the majority were biblically literate nor had much interest in what the Bible taught (exceptions noted and allowed).

3. Exegetically, I cannot see where Deut. 17:14,15 is relevant to the matter of who is qualified to be President of the United States, nor more generally, who should be considered a citizen of the United States. One would have to prove that the passage is paradigmatic and universally binding and that would have to apply to every country in the world without exclusion.

I am going to assume that what we could agree on is that SCOTUS (Supreme Court of the United States) has made some horrible judgments in its history, some of which I strongly believe are contrary to the U.S. Constitution and many certainly antithetical to God's moral law. Because we are the blood-bought children of God it is HIS law to which we unfeignedly obey and most gladly regardless of what any man rules in a court of law or what any government enacts as law. God alone is LORD of the conscience.