Pat, you seem to be arguing that the Constitution protects individual religious beliefs, rather than the stated beliefs of a particular institution, which is the position the bishops appear to be defending. I'm not sure the Constitution aims at protecting individual beliefs or individual interpretations of a religion's beliefs, but then I'm not familiar with the judicial history. 
My uneducated guess is that the founders aimed at protecting what Christians believe and practice, what Jews believe and practice, and so on -- as defined by their religious authorities. If I were to claim religious liberty based on the fact that I'm a Catholic who believes that sick people should be left to die, I don't think the courts would rule in my favor. So, in that view, what the public says is only relevant to the Constitution to the extent the people can bring about change in their respective denominational teachings. Please correct me if I'm wrong.