History books tend to oversimplify the early history of America in order to obfuscate a few inconvenient truths about the founding of our nation, so allow me to clarify a couple of things:
It is correct to say that the original settlers from England came here to, among other things, escape religious persecution. The beliefs of the Puritans, the Quakers, and others were actually significantly MORE radical than the Church Of England’s doctrine. This comes as no surprise when you consider that Henry VIII broke from the Vatican and started the Church Of England essentially so he could divorce his wife. The CoE paid little more than lip service to the dogma and the doctrine of Protestant Christianity, and the response from certain sects of more conservative-minded Protestants was to start their own splinter faiths, which actually began to gain in popularity enough to cause some consternation on behalf of England’s theocratic leaders, resulting in anything from mild discrimination to outright acts of violence.
It’s important to note, however, that the span of time between the landing at Plymouth Rock(1620) and the drafting of the Declaration Of Independence(1776) is over 150 years, and in that time, a great deal had changed. Once the colonies were firmly established and trade routes between Europe and the New World were set up, the prevailing attitudes towards religious faith shifted much more towards agnosticism, particularly in the North. The enforced distance between the colonies and England, as well as the massive influx of colonists to the New World from various European countries, brought with it a much more lax and even outright resentful attitude towards theocratic rule and its endless warmongering, brutal taxation practices, and unilateral authority(sound familiar?), particularly among the elites. It is with these things in mind that the Framers of the Declaration of Independence and the Constitution penned both of these documents, ensuring that our nation was founded on secular values, not Judeo-Christian doctrine.
While lip service was still paid to religious faith as a matter of principle, mainly to avoid disfavor with the general populace, on a more private level men like Washington, Jefferson, Franklin, and Adams had much more agnostic leanings. Jefferson and Franklin in particular professed to be atheists later in life, when their political careers were no longer at stake. This is the societal framework under which the First Amendment was created, formally establishing for the first time in history an official separation between Church and State.
The Establishment Clause is NOT the work of religious men, as every major monotheistic belief has codified within its doctrine a ‘might makes right’ philosophy that decrees it to be above all others, with a commandment to exert its influence even at the point of a sword if necessary, but most often with the tip of a pen through royal decree at the time. The prevailing belief that America was founded on Judeo-Christian values is an outright lie, a false narrative created by the Right to appeal to people’s sense of faith, duty, and nationalism. The sad thing is, it’s worked all too well over the last several decades to distort the truth, and until the Left can come up with an effective counter-narrative - one that appeals to the same set of values - this narrative will continue to be the dominant one, and the Right will, over the course of the next couple of generations, literally rewrite history.