Perhaps, though, there is one person who, more than any other, influenced the founding documents of our nation. That would be Thomas Paine. His pamphlet, Common Sense, was written at the time of the Declaration of Independence, and was intended to give intellectual support to the Revolution and to advocate for the establishment of a secular government, with full freedom of religion to all.
I read this in its entirety a decade or so ago, and it was a thoroughly enlightening experience. This should not be surprising, because Paine’s pamphlet is full of Enlightenment ideas. He challenges the idea that kings - and governments - are established by god. Instead, he argues (from the Bible in addition to other sources) that mankind was originally equal, not hierarchical, and that government was established by humans to protect ourselves against each other. Thus, the source of government is - or at least should be - a social contract between equal humans for the mutual benefit and protection of all. This was, at the time, a radical idea, and one directly opposed to the Divine Right of Kings so beloved by Charles I.
I should mention too that Paine’s other great work was The Age of Reason, one of the key Enlightenment texts. In it, he took some bold steps. The first was to challenge the established Church, which Paine believed had been corrupted by its thirst for political power. He also took issue with the Church’s quest for power and profit - a charge that seems rather relevant today. In his view - which I share to an extent - the true religious duties should be “doing justice, loving mercy, and endeavoring to make our fellow-creatures happy.” (See, for example, Micah 6:8 and James 1:27.) The word "happy" in this era would refer to "well being," not a state of mind. So in other words, making them "happy" would mean to make their lives better. This is echoed in the Declaration of Independence as the right to “life, liberty, and the pursuit of happiness.” That is, the right to pursue a decent life for one’s self.
But perhaps the most controversial idea was this: he rejected the idea of laws based on “special revelation,” arguing that instead reason and “natural law” should be the basis of civil government. As Paine (quite correctly) pointed out, revelation to one person is second hand to another. Likewise, in his observation (and mine too), the so called “revelations” seem to have changed over time to accommodate different political circumstances. (See: slavery.)
In addition to the more general ideas, Common Sense contains a proposal for an ideal constitution. Paine clearly intended it to serve as an example for the newly independent United States of America. In fact, many of his proposals were in fact adopted in the Constitution of the United States.
Jefferson himself quoted Paine extensively in his writings, and his idea of a “wall of separation” hearkens back to Paine - and to Roger Williams and William Penn. And, like Paine, he believed that the basis for civil government needed to be reason and natural law, not rules drawn from a sacred text or the teachings of a religious leader.
This is the actual history.