I'm most interested in Fea's current project! Not even many Freemasons understand the significance of the Paul Revere's Lodge in Boston having it's charter from the Grand Lodge of Scotland, rather than from the Grand Lodge of England!
I look forward to buying a copy!
In reference to this part of your posting:
"The First Amendment did not originally apply to individual states--it simply prevented the federal Congress from officially endorsing any one specific "religion" as the national church."
Part of the reason for the "slippery slide" from the Federal realm to the state level was the growing awareness that it was just as painful to some if a state favored one denomination over another as it was when the National government did the same thing.
Post Script: Oh... I was supposed to comment on the book you linked to:
"Was America Founded As a Christian Nation?: A Historical Introduction"
I'm not sure having a definite Yes to the title question even gets us to where you are trying to go.
America could have been intended as a Christian Nation, and then it evolved from there.
America could have been intended as a Christian Nation, but with no firm idea that
the Government should lead the way. By your own admission, the Federal Government was not supposed to lead the way. So that makes for an ironic twist, yes?
When you add the fact that Jesus isn't mentioned at all in the Constitution... can we really make much of a case for the country being Founded as a Christian Nation?
What we know for sure is that Christians (plus some others) were overwhelmingly the Founders of the nation.
And based on the social studies curricula provided me as a child, what I see is a country that was intended to cultivate diversity. And that diversity of religion - - somthing that Englishmen had direct experience ever since the time of Cromwell - - was certainly part of the equation.
The book "The American Democracy" by Alexis de Tocqueville made some keen observations. One of them was that in America, it didn't really seem to matter what church a person attended ... as long as a person attended one. Naturally, at the time, the population was overwhelmingly Christian, but this American characteristic still rubbed off on Good Jewish Citizenry ... who were regular visitors to Synagogue.