What about the Aztecs?
In religious matters. The goverment does not have the right to tell people of faith how to practis their religion. Just because all of you don’t agree with the LDS doctrine it does not give the government the power to tell them , you or I how to worship.
So you are endorsing child rape? Jeffs was just sentenced for having sex with a 12 year old 'wife' (among many other pre-teens). That was a part of his worship.
What about the Aztecs?
If I understand you correctly, you are saying, basically, that the Government cannot restrict how you worship and what you believe. The Constitution states in the first amendment: "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof.". The interpretation of that, of course, has been a boondoggle for lawyers ever since. There was a Supreme Court decision in Sherbert v. Verner, 374 U.S. 398 (1963), where they required that states have a "compelling interest" in refusing to accommodate religiously motivated conduct.
So, I would surmise from this that the government can only interfere with the free exercise of religion when there is a compelling cause. When the LDS religion first started, there were already laws against polygamy. Smith chose to disobey those laws AS a U.S. citizen, so he was in violation of the law. It would have been different if Smith's religion existed before there was a U.S. Constitution, but that was not how it happened. If it were, then perhaps there would be something about such things in the Constitution that would allow exceptions in certian cases. But it didn't in the LDS case.
For example, the same would apply to Santeria. It is a combined Caribbean/West African religion with some Roman Catholicism mixed in, that, among other things, sacrifices live chickens in their worship. The first Santeria church established in the U.S. was in 1974 (per wikipedia.org). There have been controversies with it and American law. One in particular addressed their treatment of animals. In 1993, the issue of animal sacrifice was taken to the United States Supreme Court in the case of Church of Lukumi Babalu Aye v. City of Hialeah. The Supreme Court ruled that animal cruelty laws targeted specifically at Yoruba were unconstitutional; the Yoruba practice of animal sacrifice has seen no significant legal challenges since then. But when a woman died because her mother thought she was demon possessed and had put a plastic bag over her head to smother her in an exorcism ritual, then the mother was prosecuted for murder. The mother was found not guilty due to insanity, and is currently confined in a New York State psychiatric hospital for the criminally insane.
So, I think the Constitution prevents the government from restricting the free exercise of religion, but when any religion violates federal or state laws, it must adhere to the law unless the courts find a compelling interest in favor of the religion. I don't see any sign of the government threatening established religions in this country and, if they did, as we see in Muslim or communist countries, I believe we have the Constitution on our side and we would not permit such without an unrelenting fight.