The Founding Fathers did not create the universe. Furthermore, there are atheist "conservatives" who deny that our rights come from G-d.
As those rights are God-given, to block them with a theocracy is not only un-American, but in defiance of God.
The right to do what? To murder? Isn't that illegal already? So what's the big deal? Or how about to steal? No? We've already got a law against that? And you aren't complaining about how tyrannical it is? Or maybe the right to be "gay" or have abortions for convenience?
So what is it about a theocracy that is so scary? The laws are already in force. But nothing less than the Will of the Creator can justify such laws!
As to whether or not "all mankind" has the "right" to worship any other "gxd" than the Jealous G-d of Israel, I think His instructions on the matter carry more wait than the opinions of Jefferson, Paine, Voltaire, or anyone else (however "un-American" that makes me).
Very simple. One does not have the right to murder, because it denies a person the right to live. We do not have rights to violate the rights of others. (And in the many cases where it's hard to tell what the respective rights are, we have courts.)
So what is it about a theocracy that is so scary? The laws are already in force. But nothing less than the Will of the Creator can justify such laws!
A theocracy is scary because people are imperfect. As such they may well imperfectly interpret what God wants us to do. In their misinterpretation, they may compel others to act against God.
Obedience to and worship of God must be a free act. To compel it with a theocracy is to make such obedience and worship worthless. As such, a theocracy is an insult to God. Likewise, your call for a theocracy is an insult to God.
If you don't like living under the US Constitution, there are alternatives.