This is not to say that the deepest concerns of the faithful, whether moderate or extreme, are trivial or misguided. There is no denying that most of us have emotional and spiritual needs that are now addressed--however obliquely and at a terrible price--by mainstream religion. And these are needs that a mere understanding of our world, scientific or otherwise, will never fulfill. There is clearly a sacred dimension to our existence, and coming to terms with it could well be the highest purpose of human life. But we will find that it requires no faith in untestable propositions--Jesus was born of a virgin; the Koran is the word of God--for us to do this.