Most of the founding fathers where enlightenment thinkers. A handful were (based on their writings and actions) believing Christians such as Noah Webster, Patrick Henry, Samuel Adams.
Others were sympathetic to Christianity, however they mixed the holy (God’s wisdom from scripture) with the profane (Greek, humanist, pagan, and enlightenment philosophy). They would pick and choose from various wisdom literature sources including the Bible, Voltaire, John Locke, Rousseau, Montesquieu, Freemasonry, etc.
You will often find men such as Gouverneur Morris, Thomas Jefferson, George Washington, Benjamin Franklin, and John Adams making public comments, speeches, and legislation that would include Christian friendly terminology. Then their private letters would reveal their condescending ridicule and even open hostility toward the Christian faith.
To reconcile this difference, you only need to realize that human nature has not changed over the last 6,000 years. Politicians back then are the same as politicians today. They will say whatever it takes to get people to follow them.
It is not strange that their public and on record remarks are very carefully worded so as not to offend Christians. The vast majority of the colonists at the time of the Revolution were Christian. The Puritans and Pilgrims were Christian and purposefully came to the new continent for the purpose of spreading the Gospel and living out their Christian faith. They wanted a Christian Nation, and this is evident by the charters of the various colonies and constitutions of the various states. They intended to establish Christianity as the official religion of their colonies.
The Enlightenment thinkers, however, leveraged the differences between the various denominations to include language in the founding documents of the federal government for “religious freedom”. In the minds of the general Christian populace, this meant that not one denomination would be superior or enforce it’s distinctions over another. In the minds of the Enlightenment philosophy, religious freedom meant freedom for all religions with the ultimate goal of freedom from religion.
Some were openly hostile to Christianity such as Thomas Paine. Yet, Thomas Paine used very Christian language in Revolutionary War propaganda such as “Common Sense”. Yet in his other works such as “The Age of Reason” it is very clear that he is very anti-Christian. It is interesting to note that Thomas Paine was a Mason and lived with a man who was a member of the Bavarian Illuminati. Paine was not out to inspire a Christian revolution, he was motivating Christians to support and participate IN the revolution.
Now don’t think that I’m trying to say that our country is bad or the Constitution is a bad thing, etc. As far as human governments go, it is about as good as it could possibly get. I support the Constitution and believe that it is the only thing (besides God’s intervention) standing between us and a socialist tyrannical government. However, I do not need to “Christianize” the Constitution or our federal government system in order to believe that it is worth protecting. There are good and valuable things in our founding documents, but they are not scripture. The Founding Fathers are great men who risked (and lost) much, and we owe them a debt gratitude, but they are not saints or demigods.