The Faiths of the Founding Fathers (Oxford Press, 2006). He discusses the religious environment of 18th century America and the influence of British deism. He has entire chapters on the religious views of Benjamin Franklin, George Washington, John Adams, Thomas Jefferson, James Madison, James Monroe, as well as others. His conclusion is that the founding fathers could be grouped as follows:
Non-Christian Deists: Thomas Paine, Ethan Allen.
Deistic Christians/Unitarians: Ben Franklin, George Washington, John Adams, Thomas Jefferson, James Madison, James Monroe.
Orthodox Christians: Patrick Henry, Samuel Adams, John Jay, Elias Boudinot, John Witherspoon.
The difference in the Non-Christian Deists and the Deistic Christians/Unitarians is that the latter believed that many of the teachings of Jesus were worthy of emulation. They gave Jesus a special place in their theology although not the place of God as in orthodox Christianity. Confusion often arises because most of the Founding Fathers mentioned "God," or "the Creator," or "Providence" in their speeches and writings. Yes, they believed in a divine being; they were not atheists (there were very few public atheists at this time). However, the fact that they mention God does not mean that they are orthodox Christians either.