Here is my favourite quote about how gullible people are that they would remain part of the religion after such a failed prediction. It makes it embarrasing to be human.
Doctrines that make no predictions are less compelling than those which make correct predictions; they are in turn more successful than doctrines that make false predictions.
But not always. One prominent American religion confidently predicted that the world would end in 1914. Well, 1914 has come and gone, and -- while the events of that year were certainly of some importance -- the world does not, at least so far as I can see, seem to have ended. There are at least three responses that an organized religion can make in the face of such a failed and fundamental prophecy. They could have said, "Oh, did we say '1914'? So sorry, we meant '2014.' A slight error in calculation. Hope you weren't inconvenienced in any way." But they did not. They could have said, "Well, the world would have ended, except we prayed very hard and interceded with God so He spared the Earth." But they did not. Instead, they did something much more ingenious.
They announced that the world had in fact ended in 1914, and if the rest of us hadn't noticed, that was our lookout. It is astonishing in the face of such transparent evasions that this religion has any adherents at all. But religions are tough. Either they make no contentions which are subject to disproof or they quickly redesign doctrine after disproof. The fact that religions can be so shamelessly dishonest, so contemptuous of the intelligence of their adherents, and still flourish does not speak very well for the tough-mindedness of the believers. But it does indicate, if a demonstration were needed, that near the core of the religious experience is something remarkably resistant to rational inquiry.
Broca's Brain Carl Sagan (New York: Ballantine Books, 1979, pp. 332-333)
