Thomas Jefferson, letter to Peter Carr

"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, August 10, 1787

Scanned letter at The Library of Congress