I happened upon this article recently and found it very revealing:
http://www.constitutionmythbusters.org/national-religious-freedom-day-aka-celebrating-the-founders-violation-of-the-first-commandment/
Not only is it short and to the point, but it has opened my eyes to a false belief which so many of us have been taught from our youth, and thereby accept, even now as adults, without question.