Whenever an argument arises about the role that religion should play in our civic life, such as the dispute over the phrase "under God" in the Pledge of Allegiance or the display of the Ten Commandments in an Alabama courthouse, assertions about the faith of the founders are invariably bandied about. It's a wonderfully healthy debate because it causes folks to wrestle with the founders and, in the process, shows how the founders wrestled with religion.
The only direct reference to God in the Declaration of Independence comes in the first paragraph, in which Thomas Jefferson and his fellow drafters of that document--including Benjamin Franklin and John Adams--invoke the "laws of nature and of nature's god." (The absence of capitalization was the way Jefferson wrote it, though the final parchment capitalizes all four nouns.) The phrase "nature's god" reflected Jefferson's deism--his rather vague Enlightenment-era belief, which he shared with Franklin, in a Creator whose divine handiwork is evident in the wonders of nature. Deists like Jefferson did not believe in a personal God who interceded directly in the daily affairs of mankind.
In his first rough draft of the Declaration, Jefferson began his famous second paragraph: "We hold these truths to be sacred and undeniable ..." The draft shows Franklin's heavy printer's pen crossing out the phrase with backslashes and changing it to "We hold these truths to be self-evident." Our rights derive from nature and are secured "by the consent of the governed," Franklin felt, not by the dictates or dogmas of any particular religion. Later in that same sentence, however, we see what was likely the influence of Adams, a more doctrinaire product of Puritan Massachusetts. In his rough draft, Jefferson had written, after noting that all men are created equal, "that from that equal creation they derive rights inherent & inalienable." By the time the committee and then Congress finished, the phrase had been changed to "that they are endowed by their Creator with certain unalienable Rights." For those of us who have toiled as editors, it is wonderful to watch how ideas can be balanced and sharpened through the editing process (and also how even giants have trouble knowing whether the word is inalienable or unalienable). The final version of the sentence weaves together a respect for the role of the Almighty Creator with a belief in reason and rationality.
The only other religious reference in the Declaration comes in the last sentence, which notes the signers' "firm reliance on the protection of divine Providence." Most of the founders subscribed to the concept of Providence, but they interpreted it in different ways. Jefferson believed in a rather nebulous sense of "general Providence," the principle that the Creator has a benevolent interest in mankind. Others, most notably those who followed in the Puritan footsteps of Cotton Mather, had faith in a more specific doctrine, sometimes called "special Providence," which held that God has a direct involvement in human lives and intervenes based on personal prayer.