The following is an edited excerpt from The Belief Instinct, which will be published Feb. 7.
Consider, briefly, the implications of seeing God this way, as a sort of scratch on our psychological lenses rather than the enigmatic figure out there in the heavenly world that most people believe Him to be. Subjectively, God would still be present in our lives. (For some people, rather annoyingly so.) He would continue to suffuse our experiences with an elusive meaning and give the sense that the universe is communicating with us in various ways. But this notion of God as an illusion is a radical and, some would say, even dangerous idea because it raises important questions about whether God is an autonomous, independent agent that lives outside human brain cells, or instead a phantom cast out upon the world by our species' own peculiarly evolved theory of mind. Since the human brain, like any physical organ, is a product of evolution, and since natural selection works without recourse to intelligent forethought, this mental apparatus of ours evolved to think about God quite without need of the latter's consultation, let alone His being real.
Then again, one can never rule out the possibility that God microengineered the evolution of the human brain so that we've come to see Him more clearly, a sort of divine LASIK procedure, or scraping off the bestial glare that clouds the minds of other animals.
Either way, this cognitive capacity, this theory of mind, has baked itself into our heads when it comes to our pondering of life's big questions. Unlike any science-literate generation that has come before, we now possess the intellectual tools to observe our own minds at work and to understand how God came to be there. And we alone are poised to ask, "Has our species' unique cognitive evolution duped us into believing in this, the grandest mind of all?"