I want to address here one of the big lies that conservatives say about America, that it is a Christian nation. These people therefore think that Christianity is an important component of America while in all actuality Christianity has nothing to do with America.
The best word to use to describe the Founding Fathers is "deism". Deism is the philosophy (it is not a religion) that the harmony and well-order of the universe points to some sort of Cosmic Architect. Many deists do not even like saying "God", they might say "Nature's God" or "Creator" or even more simply "First Cause". It is not a religion because deists do not believe in miracles, they do not believe in revelations, they do not believe in the supernatural, and they do not even believe in afterlife. Deists embrace science and Reason, they also hate faith. Deists accept all science and reject ideas such as souls or creationism, so on and so forth. Deists say they do not know anything about what God (or this Architect) is. They also say that God is not a personal God, in other words, God does not intervene with the world. The universe exists by itself with no one guiding anything, it runs by itself, and that we (humanity) are just creations within the universe. Therefore, prayer is useless because God is not involved in the lives of people, rather people need to be involved with the lives of people. For these many reasons deism has absolutely no emotional satisfaction whatsoever, unlike religion. It has no meetings, Churches, or dogmas, it therefore cannot be called a religion at all, it is just a philosophy.
It is important to contrast deism with theism. Theism is the belief in a personal God, an entity that formed the entire universe, guides it, watches over it and humanity, has a plan with people, wants to send it goodness onto them, gives afterlife, ... so on and so forth. Religions (with an exception of a few like Scientology) are theistic. An "atheist" is someone who "is not a theist". Thus, if one does not believe in a personal God then he is an atheist by that definition. This means that deism is a subset of atheism.
The main Founding Fathers of America were not Christians, they were deists (and therefore atheists). These include: George Washington, John Adams, Thomas Jefferson, James Monroe, Benjamin Franklin, and Thomas Paine. Washington is the only one that had little to do with Christianity, but still nonetheless he was not a Christian. While Jefferson was completely opposite of Christianity. Jefferson even rewrote the entire Bible in what he called "Jeffersonian Bible" because he had respect for Jesus, even though he did not believe in him. Jefferson rewrote the New Testament to remove all the miraclous stories and replace them with basic moral teachings. This just shows how un-Christian he was. But of all Thomas Paine was the most violent towards Christianity. Paine wrote in 1794 a book called "Age of Reason". It was the first open attack anyone has ever made against organized religion. During the Enlightenment philosophers were afraid of being persecuted by the Church, Paine was the first one ever to openly write a book against it.
The Declaration of Independence even does not say "God", it says "Nature's God" and then later "Laws of Nature". If these were Christians writing the Declaration of Independence we should expect "Jesus" or "Lord", but this is never used anywhere. The Constitution makes NO mention of "God" anywhere, not in the beginning, middle, or end. Christopher Hitchens said that America is actually the most secular nation in the world if we consider its founding principles. Even secular nations in Europe, England for example, are still tied with the Church. America is the only nation that has the principle that religion cannot be supported by the state. The Founders included it in the first admendment because they realized how important this seperation really is. One should also read through the quotes of the Founders to realize how they felt about making America a religious nation. America has been made into a 100% secular nation, this is not even an opinion this is a historical fact. Of course, this does not mean that religion should be banned or atheism to be imposed on the citizens, it rather means that these ideas cannot be part of government. People can believe whatever they want to believe in, they just cannot use those beliefs for justification of certain ideas about government.
Here are some additional videos supporting or adding to my point: