The U.S. Constitution does plainly state there is a separation of state and religion, hence anyone trying to violate it is simply wrong.
Religion is protected, though. You can worship in anyway you like, to whatever god or denomination you prefer, but when folks enter government and try to use it like the “Spanish Inquisition,” then that is why we have our constitution.
Some dislike this and pay lip service to the Constitution only when it supports their personal agendas.
Our forefathers came from countries where one could be burned at the stake, put to the rack and tortured in many unimaginable ways for merely having a different theology or denomination. They knew the danger of zealots with power, and hence, they placed a bar in the Constitution so these zealots to would not have power.
I believe in God, but I have no right to impose my views on my neighbor.