True, and they wanted to keep religion out of government because they had just won independence from the monarchy that established the "Church of England". They knew how problematic it was when the head of state is also the head of the church. Separation of church and state protects both entities; mixing them de-legitimizes both. Modern evangelicals seem to have forgotten that.
The whole "Christian nation" thing makes me nervous. A lot of the founding fathers were deists or agnostics.
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