I'm not a legal scholar, as should be obvious, but didn't the 14th amendment extend the bill of rights to the states level, forcing the individual state to adhere to the establishment clause?
Before the 14th amendment passed, it was only the federal government that was bound by the bill of rights, but afterwards it was all government.
This means that it would not be unconstitutional for a state to have state sponsored church befor the 14th amendment passed in 1868. So your example is not relevant today!
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