Bloody Mary
The separation of church and state protects the church as much as it protects the state. Consider Bloody Mary. No, not the creature that lives in your bathroom mirror in the middle of the night, and if you say her name three times with the lights off she kills you. The one she was named after, who burned almost three-hundred religious disenters at the stake for not going along with her version of the Church. What happens without the first amendment? Churches take over the government, and it might not be your church.
Within the Protestant church system alone there are around thirty-five thousand different denominations. Many of these unite under the banner of evangelicalism today, but if any one of them took over? That's when the cracks show. The first amendment was to prevent America from turning into the bloodbath that Europe had once been. That's one of the reasons we have to continue to fight for it. This podcast episode gets into how that boundary between church and state is being hammered on by the evangelical community today.