Dennett is of course not alone in his essentialist definition of the complex phenomenon of religion (although it is worth noting that William James resisted developing such definitions). Stephen Prothero rightly points out that virtually all of the New Atheists, Dennett included, have tended to “load all religions into one boat.” Prothero suggests a way beyond essentialism by talking about ‘family resemblances’ rather than looking for some common essence of all religion. A more robust definition of religion may have significantly improved Dennett’s work, perhaps something like philosopher Ninian Smart’s theory of religion’s seven dimensions: ritual, narrative, experiential, institutional, ethical, doctrinal, and material dimensions. On the other hand, a more complex definition of religion such as this would have complicated the delivery of Dennett’s main point: that all ‘religion' can be explained as a purely natural phenomenon.
Dennett then moves to discuss the evolution of the human brain by arguing that there was a crucial evolutionary adaptation, which he calls HADD: ‘hyperactive agent detection device.’ This “fiction generating contraption” made humans attribute mind or agency to “anything that puzzles or frightens us.” This gave birth to animism, the earliest expression of religion in which nature is attributed the additional status of spirit. So for Dennett, religion was not ‘chosen’ by humans based on what we presently understand as religious experience or revelation – it arose naturally, purely through the impersonal processes of biological and cultural evolution. From this basic method, he provides his own ‘natural history of religion’ that describes the evolution of religion from animism, to deities, to present forms of theistic religion.
Furthermore, this same evolutionary approach that Dennett uses can be applied to just about anything in human experience: “Everything we value – from sugar and sex and money to music and love and religion – we value for reasons. Lying behind and distinct from, our reasons are evolutionary reasons, free-floating rationales that have been endorsed by natural selection.” Dennett seems to get a thrill out of trying to convince us that our experiences are illusory, ultimately due to natural selection: “We don’t love babies and puppies because they’re cute. It’s the other way around: we see them as cute because evolution has designed us to love things that look like that.” While evolution has blindly designed us for certain things apart from the behavior of organisms, Dennett takes this to the deterministic and reductionistic extreme. This of course rests on his dogmatic commitment to mindless matter as the ‘really real’, when in fact many philosophers would see this as a very problematic position.