My personal idea (pardon my lousy english):
"Religion is the conviction that the emperor wasn't nude after all."

By the way, I think a similar campaign highlighting the worst quotes of the Bible (perhaps combined with realistic illustrations of what the verses actually say?) would be a great way of eroding the moral status of christianity in the eyes of the public. Some hot candidates might be:

"slay both man and woman, infant and suckling, ox and sheep, camel and ass" (1. Samuel 15:3)"
"I will make them eat the flesh of their sons and the flesh of their daughters" (Jeremiah 19:9)
"How blessed will be the one who seizes and dashes your little ones Against the rock" (Psalms 137:9).
"Their little ones will be dashed to pieces Before their eyes; Their houses will be plundered And their wives ravished" (Isaiah 13:16).
"Their little ones will be dashed in pieces, And their pregnant women will be ripped open" (Hosea 14:1).
"Cursed be the one who does the LORD'S work negligently, And cursed be the one who restrains his sword from blood" (Jeremiah 48:10).