Ever read the constitutions of the various states? Many of the men who ratified the first amendment lived in states which had tax supported religions.
When I was in elementary school, there was still prayer in the public schools. Every morning we had assembly. The Protestant teacher would lead us in the Protestant version of the Lord's Prayer. When she got to the part about "For the kingdom, the power, and the glory . . . ," there would be almost complete silence, since almost 100 percent of the kids were Catholic. That is my experience of state-sponsored religion.
So tell me about the state constitutions again?