And that's ALL our constitution forbids. "Congress shall make no law respecting an establishment of religion." No one has to sign up. No one has to register. You can still vote. That is, there's no law about an established religion.
What I understand is that you don't like it that Judge Moore is a true believer in his own religion. Is it surprising to you to find out that true Baptists think their religion is right and that all others are anywhere from less right to wrong. And Catholics are the same. And Hindus are the same.
But, here's one for you. Judge Moore is a citizen of the state of Alabama, and according to their own Constitution, Section 3: and that the civil rights, privileges, and capacities of any citizen shall not be in any manner affected by his religious principles.
Judge Moore's allowed to believe anything he wants in the area of religion AND it shall not affect any of his rights, privileges, and capacities. But this is the same as the US Constitution "or prohibiting the free exercise thereof."
All I can guess is that you don't know the difference between common law and statutory law.
What I understand is that you don't like it that Judge Moore is a true believer in his own religion.
I like it just fine. I'm a true believer in mine. It's called Protestantism - you may have heard of it... it started out rather well as an attempt to get the government to stop ordering people to obey certain religious doctrines, but then went south when its adherents gained the upper hand and started doing the same thing. Some people never learn. Moore certainly hasn't.
Judge Moore's allowed to believe anything he wants in the area of religion
Absolutely. But he's not allowed to declare his beliefs to be superior to the law of Alabama or of the United States.