The naturalist has to say that spiritual experiences are illusory. It is bad enough that the naturalist has to say this about such a large class of human experiences. But these experiences are central among the experiences that give life its savor, they are among the deepest and most significant of human experiences. Indeed, all of the deepest and most significant of human experiences include an aspect of the spiritual: the person I have encountered is seen clothed in a a significance that organic chemistry could never have, the vista stretching out before one in the night sky bespeaks a mystery beyond the merely puzzle, and so on. The naturalist has to say of the deepest and most significant of human experiences that they are illusions. And that is surely a problem.