I used the definition of Freemasonry as a religion because for many of the founding fathers, the practice of Freemasonry and attendance at Masonic meetings was likely far more influencial on their lives than any religion practiced. Freemasonry can be seen as a philosophy much akin to religion.
As to the constitution, it is a wise document. The writers clearly understood the dangers of mixing religion and politics, and framed the constitution with that in mind. The establishment clause was a reaction the European practice of fomenting a state religion. They truly wanted a country where one's religion, or lack thereof, would in no way be a determining factor in one's political aspirations, or on the holding of public office.
Were they influenced by their upbringing and culture? Certainly, but the wording of the constiturion does manage to convey the ideal outlined in the previous paragraph.
There is a danger to freedom and democracy when a person's religious affiliation and personal beliefs becomes the determinant factor in electability. Clearly the constitution says it should not. Reality shows that for regular folks, one's beliefs can become a determining factor in how they vote, but that is contrary to the spirit of the constitution, ie there shall be no religious "test" required to hold public office.
Religion is a touchy subject, fraught with danger to democracy. Once that road is travelled down, we can look to various theocracies in the world and clearly understand the dangers of mixing one's political beliefs with one's deeply held, personal religious beliefs. If we judge each other's character based upon our differences in personal beliefs, we endanger all of our freedoms.
Religion, that is, a person's belief system, should be a very personal experience, and should be a uniter. Instead, it becomes a divisive thing, where we, as imperfect humans, expect and sometimes demand that we should all hold the same convictions, or be "cast out" and denied the opportunity to accomplish good for our country. This creates schisms based soley on deeply personal beliefs, and not on that which unites us.
The bible clearly states that one should judge not, lest we be meted the same judgement, and that the judging and punishment belong to God only. We, as imperfect humans, are not qualified to judge a person solely upon that persons religious beliefs, or lack thereof. I speak not of laws or societal punishments for infringing upon other's rights, rather, the idea that one's beliefs are deeply personal, and vary significantly between individuals.
I'm all for religious freedom, provided that freedom does NOT infringe upon my right to believe or not believe, according to my own concience. No one has the right to deny my personal beliefs, or to force their beliefs on me. That is why the constitution is worded the way it is. Freedom is more than a nice patriotic word, it is the life force behind the U.S. constitution.
Hank's prosepctive gutiar player said: "Mr Williams, I'm not sure I can play for you, the onliest chords I know are C D & G"
Hank repleis, after a short pause: "Well, what else is there?"