Well... "founders" is more accepted in writing these days, considering someone finally figured out that there were women helping things along. But I still hear this phrase quite frequently and try to grit my teeth rather than scream. (In the same way as when someone refers in writing to a country as "she.")
"The Government of the United States is not in any sense founded on the Christian religion. The doctrine of the divinity of Jesus is made a convenient cover for absurdity..."
-- President John Adams
"What influence in fact have Christian ecclesiastical establishments had on civil society? In many instances they have been upholding the thrones of political tyranny. In no instance have they been seen as the guardians of the liberties of the people. Rulers who wished to subvert the public liberty have found in the clergy convenient auxiliaries. A just government, instituted to secure and perpetuate liberty does not need the clergy."
-- President James Madison
"I have examined all the known superstitions of the world, and I do not find in our particular superstition of Christianity one redeeming feature. They are all alike founded on fables and mythology. Millions of innocent men, women, and children, since the introduction of Christianity, have been burnt, tortured, fined, and imprisoned. What has been the effect of this coercion? To make one half of the world fools and the other half hypocrites; to support roguery and error all over the earth.
The clergy converted the simple teachings of Jesus into an engine for enslaving the world and adulterated by artificial constructions into a contrivance to filch wealth and power to themselves...these clergy, in fact, constitute the real Anti-Christ."
-- Thomas Jefferson
"The Christian religion is a parody on the worship of the sun, in which they put a man called Christ in place of the sun, and pay him the adoration originally paid to the sun."
-- Thomas Paine
You're right, Kewpid--these words are far more incendiary than Obama's "cling to guns" comment.