The Founding Fathers were cosmopolitan intellectuals devoted to the rationalism of the Enlightenment, but they were not, for the most part, humanistic atheists or opposed to religion. On the contrary, they regarded morality as indispensable to a healthy state and religion as a primary foundation of morality, as well as of charity and concern for one’s fellows. But the state itself should be secular.
Martin quotes John Adams, who lauded government “founded on the natural authority of the people alone… without a pretense of miracle or mystery;” such a government favors “the rights of mankind.”
Martin also quotes the 1797 treaty with Tripoli as signed by President Adams:
As the Government of the United States is not, in any sense, founded on the Christian religion; as it has in itself no character of enmity against the law, religion or tranquility of Musselmen [Muslims]… it is declared by the parties that no pretext arising from religious opinion shall ever produce an interruption of harmony existing between the two countries.
“Not, in any sense, founded on the Christian religion.”
Clearly the nation’s founders were influenced both by the Enlightenment and by Christianity. The simplistic argument that the nation was founded on Christianity because many of the founders were Christian neglects to sort out the causes. What was unique to America’s founding was the Enlightenment, not Christianity, which had dominated Western politics for centuries.