"The name of American, which belongs to you, in your national capacity, must always exalt the just pride of Patriotism, more than any appellation derived from local discriminations. With slight shades of difference, you have the same Religeon, Manners, Habits & political Principles. You have in a common cause fought & triumphed together--The independence & liberty you possess are the work of joint councils, and joint efforts--of common dangers, sufferings and successes." -- George Washington, Farewell Address, 1796.
It was an accurate description of the America at the time; entirely Protestant with a smattering of Catholics.
And it frankly has nothing to do with separation of Church and State.
Separation of Church and State is the REASON this country is so religious, actually; no country in the world has had it for a longer time. The countries of Europe have had (and many still have) official state-supported churches.
But quite as cool as this one:
Wait, there isn't a "Samuel Pepys" registered to FreeRepublic?(!)
Oh, then I guess yours is cooler.
Sorry for the mistake.
Carry on then!