Dude I just gave you the law and linked to the wikipedia article on the leading case, I am not trying to make a profound argument, I am just telling you have taken Con Law and First Amendment classes in law school, things are never as simple as they seem. I am not saying there is no merit to your argument, but you are talking in such extremes. If you do that in law school you will get crushed.
But since you want to play lawyer/law student, I am happy to play the part of judge/law professor.
So Mr. Dissident, explain how they First Amendment's free exercise clause is being violated?
Make sure to consider:
First and most fundamentally to your case Mr. Dissident the Federal Constitution which says "Congress can make no law" yet the article only deals with a law passed by the Texas state legislature. Why in god's name would the Free Exercise clause be applicable?
Second what do you mean by religion. I don't think this cult is a religion. This was a cult and social practices were breaking the law. Maybe the cult shared some religious beliefs, but fundamentally this was a cult not a religious institute. Religious institutes have many followers across the country, this group all lived in one housing area and followed the commands of one crazy guy.
Third what does free exercise mean? The state is not prohibiting a religion. They are merely applying a neutral rule. Prohibiting a religion is saying if you go to a catholic mass you have violated the law. Here the legislature is not saying you can't have these religious beliefs they are merely saying you must follow the law that everybody else follows. Are you saying if some religion advocated human sacrifice the state would not have the power to stop them? I don't think this violates their free exercise right, explain to me what free exercise is and why its been violated here.