Some interesting quotes:

"Shake off all the fears of servile prejudices, under which weak minds are servilely crouched. Fix reason firmly in her seat, and call on her tribunal for every fact, every opinion. Question with boldness even the existence of a God; because, if there be one, he must more approve of the homage of reason than that of blindfolded fear." - Thomas Jefferson, letter to Peter Carr, Aug. 10, 1787

"On the dogmas of religion, as distinguished from moral principles, all mankind, from the beginning of the world to this day, have been quarreling, fighting, burning and torturing one another, for abstractions unintelligible to themselves and to all others, and absolutely beyond the comprehension of the human mind." - Thomas Jefferson to Carey, 1816

"I wish it (Christianity) were more productive of good works ... I mean real good works ... not holy-day keeping, sermon-hearing ... or making long prayers, filled with flatteries and compliments despised by wise men, and much less capable of pleasing the Deity." - Benjamin Franklin Works, Vol. VII, p. 75

"The United States of America have exhibited, perhaps, the first example of governments erected on the simple principles of nature; and if men are now sufficiently enlightened to disabuse themselves of artifice, imposture, hypocrisy, and superstition, they will consider this event as an era in their history. Although the detail of the formation of the American governments is at present little known or regarded either in Europe or in America, it may hereafter become an object of curiosity. It will never be pretended that any persons employed in that service had interviews with the gods, or were in any degree under the influence of Heaven, more than those at work upon ships or houses, or laboring in merchandise or agriculture; it will forever be acknowledged that these governments were contrived merely by the use of reason and the senses...." [John Adams, "A Defense of the Constitutions of Government of the United States of America" [1787-1788] from Adrienne Koch, ed., The American Enlightenment: The Shaping of the American Experiment and a Free Society, New York: George Braziller, 1965, p. 258]