"It is the duty of every man to render to the Creator such homage and such only as he believes to be acceptable to him. This duty is precedent, both in order of time and in degree of obligation, to the claims of Civil Society. Before any man can be considered as a member of Civil Society, he must be considered as a subject of the Governor of the Universe: And if a member of Civil Society, do it with a saving of his allegiance to the Universal Sovereign." - James Madison, Memorial and Remonstrance
“We have religious freedom in the USA not in spite of Christianity, but because of it.”
I’m sure you believe this, but all the evidence is against it.
From 312 AD (Constantine) through the 18th Century, Christianity dominated Europe, and so did religious oppression.
Perhaps you do not remember why the Pilgrims came here. It was to escape religious oppression. Who were they oppressed by? Muslims? Atheists? Hindus? They were oppressed by Christians.
Quite frankly the record of Christianity with regard to religious freedom is ghastly. There was even Christian religious persecution in the Colonies:
James Madison himself wrote: “That diabolical, hell-conceived principle of persecution rages among some. . . . There are at this time in the adjacent county not less than five or six well-meaning men in close jail for publishing their religious sentiments, which in the main are very orthodox. . . . So I must beg you to . . . pray for liberty of conscience for all.”
Historically, whenever religion, including Christianity, is mixed with politics, it is oppressive, and everyone without the same brand of Christianity is persecuted.
Religious freedom in this country is precisely because the founders understood if any religion gets mixed up with government, it will ultimately suppress all other varieties of religion, even if called by the same name.