Benjamin Franklin, George Washington, John Adams, Thomas Jefferson, John Jay, James Madison, and Alexander Hamilton are the men most often considered the Founding Fathers, and only 5 of them participated in the Constitutional Congress. Thomas Jefferson and John Adams were both overseas during the convention, and Samuel Adams, Thomas Paine, and Patrick Henry did not attend as they considered the articles of confederation sufficient. If you argue that the latter 5 were influential in the Constitution, then you must extend the same courtesy to any other influential person or school of thought in the nation at the time.
The first Great Awakening had already occurred in the 1730s, and scholars attribute the timing of the discontent of the colonials with British oppression directly to the Christian fervor stirred during that first awakening. The second Great Awakening would occur shortly after the Constitution was enacted; again scholars see the timing as in conjunction with the freedom of religious plurality prevalent throughout the new nation. And an influx of new religious pilgrims from Europe to the new free country. All other parallel studies of American history in the 18th and 19th centuries clearly indicate Christianity was the prevalent faith in the nation, and not by today's standards. Theology was the hobby of most folks, as evidenced by the publishing and import of books into the nation at that time.
As for the signers themselves, Charles Pinckney and John Langdon were founders of the American Bible Society. James McHenry was a founder of the Baltimore Bible Society. Rufus King helped found a Bible society for Anglicans. Abraham Baldwin was renown for his piety and devotion to his duties as a chaplain in the army during the War of Independence. James Wilson and William Paterson had prayer over juries as U. S. Supreme Court Justices. Roger Sherman, William Samuel Johnson, John Dickinson, and Jacob Broom were Christian theological authors. Here's a quote from a famous prayer offered at the continental congress, ""... That with one heart and one voice the good people may express the grateful feelings of their hearts, and consecrate themselves to the service of their Divine Benefactor; and that together with their sincere acknowledgments and offerings, they may join the penitent confession of their manifold sins, whereby they had forfeited every favour, and their humble and earnest supplication that it may please God, though the merits of Jesus Christ, mercifully to forgive and blot them out of remembrance;"
Samuel Adams, leader of the Sons of Liberty and signer of the Declaration of Independence wrote in the "Rights of Colonists" (1772) that "The rights of the colonists as Christians... may be best understood by reading and carefully studying the institutes of the Great Law Giver and Head of the Christian Church, which are to be found clearly written and promulgated in the New Testament."
Eleven of the first 13 States required faith in Jesus Christ and the Bible as qualification for holding public office.
On and on and on ... it is impossible to extricate the influence of Christianity out of the founding of our nation. Does that mean it was established to be a Christian theocracy? No. But neither was it founded in a secular vacuum, despite the best efforts of revisionists.
