That may be true, but the Constitution guarantees a Republican form of government to all the states. In the area of personal rights, the Bill of Rights is considered the supreme law of the land and whatever any state wants to enact must first be in pursuance to the supreme law of the land -- defined as the Bill of Rights and the U.S. Constitution.
This is the critical article which prevents sharia law from gaining a foothold in America.
It’s actually not true. While the 1st Amendment does apply to Congress, the courts have declared that the 1st Amendment protections apply to the states through the 14th Amendment. So, any violation of 1st Amendment protections by states is an issue in federal courts. It happens all the time.