Bruce Frohnen addresses that topic in this post over at The Imaginative Conservative: What a Constitution Can, and Can't, Do. A good read for those of use who are interested in American legal theory, or in constitutionalism in general. Frohnen's comments on the need for constitutions to be followed in practice is one that is often overlooked in discussions about constitutional law. It isn't enough to enshrine a thought into a charter, that thought has to be able to converted into action.
The wisdom of the American Founders, particularly in regard to religion, is that they were able to take their ideas and craft them into principles that both protected freedom and reflected the values and practices of late-colonial and early-republican America.