“Religion is too important a matter to its devotees to be a subject of ridicule. If they indulge in absurdities, they are to be pitied rather than ridiculed.”

To Libertines
Philosophy in the Bedroom (1795)

( Fiji Live http://www.Fijilive.com). <br class="br">Reaction to the Jyllands-Posten Muhammad cartoons controversy, 7 February 2006

Part 4, Section 7
Source: A Treatise of Human Nature (1739-40), Book 1: Of the understanding

As quoted in What Great Men Think of Religion (1972 [1945]) by Ira D. Cardiff, p. 245. Actually said by Edward Gibbonː "The various modes of worship, which prevailed in the Roman world, were all considered by the people, as equally true; by the philosopher, as equally false; and by the magistrate, as equally useful." (The History of the Decline and Fall of the Roman Empire, 1776, Vol. I, Ch. II).
Misattributed

Of his paper "The Theory of Interstellar Trade"; quoted in The Economist, 26 October 2013, p. 86

Source: Death Bringer

Source: Astronomia nova (1609), Ch.58, as quoted in John Freely, Before Galileo: The Birth of Modern Science in Medieval Europe (2012)
Context: I was almost driven to madness in considering and calculating this matter. I could not find out why the planet would rather go on an elliptical orbit. Oh, ridiculous me! As the liberation in the diameter could not also be the way to the ellipse. So this notion brought me up short, that the ellipse exists because of the liberation. With reasoning derived from physical principles, agreeing with experience, there is no figure left for the orbit of the planet but a perfect ellipse.

Women Can't Hear What Men Don't Say (2000)