from: The Age of Reason

Infidelity does not consist in believing, or in disbelieving, it consists in professing to believe what one does not believe. It is impossible to calculate the moral mischief, if I may so express it, that mental lying has produced in society. When a man has so corrupted and prostituted the chastity of his mind as to subscribe his professional belief to things he does not believe, he has prepared himself for the commission of every other crime. --Tom Paine