Harris's next book will be, perhaps, his most controversial -- which is a rather impressive claim for the author of books that claim to disprove the notion of free will and call for the end of faith in America.
The conceit probably originated with Kant: Way back a long time ago we weren't so hot at science. We were babies then, so in the face of an unpredictable world we clung to our religion like mama's skirt. Now we're growing up and must put away childish things: all religion must go.
This diverse, unorganized mish-mash of open-minded seekers tends to approach spirituality in a reasonable, rational and pragmatic manner, and it's the fastest-growing religious category in America: spiritual but not religious.