I thought that was very interesting and had a great deal of truth to it, if not necessarily on the point I'm addressing, which is how the term is used here, largely, and why....Just some thoughts that may or may not advance the discussion.
One particular point in addressing the segregation of public and private morality. To my mind it's more a reflection on a changing context and thinking in relation to general principles of government that we largely failed early in the life of the Republic. On the one hand we recognized the need for an equal standing before the law and the essential equality of man before God. On the other hand we owned people and denied women and others an equal standing before the law or in the exercise of right. Similarly, it was around a hundred years from emancipation to full participation for blacks in our society.
With the church, for generations laws which favored both one religion and in some cases a particular form of it were on the books in many states and echoed in the larger federal government. Those laws often promoted the idea that many fled Europe to avoid, a state sanctioned church, if created de facto. It wasn't really addressed or much of an issue because so many of the early peoples of our nation shared the same faith and settled into communities that reflected their particular brand of it. Generations of people were born and died in those same communities. The industrial awakening of America changed that. It brought a migratory trend among the people, began to change the ease and assumption of those established communities as people entered into them with different practices and ideas. Eventually it challenged it to the point where what had been an easy and invited yoke became an obvious problem.