Considering that the brain is increasingly being credited with having a role in everything we think, feel, and do, it was probably just a matter of time before it was postulated that religious belief has a neural substrate. The question of how the brain might be "hardwired" for spirituality has captured the interest of many investigators who have established careers in fields as different as neurology, theology, and neuroscience and spawned the new discipline of neurotheology.¹

Neurotheology, neurons, and neurotransmitters
Neurotheologians argue that the structure and function of the human brain predispose us to believe in God. They claim that the site of God's biological substrate is the limbic system deep within the brain, which has long been considered to be the biological center for emotion. Rhawn Joseph, a prominent neurotheologian, goes a step further to suggest that the limbic system is dotted with "God neurons" and "God neurotransmitters."²

Among the limbic structures that have been associated with religious belief, the most frequently credited are the hypothalamus, amygdala, and hippocampus. Neurotheologians point to changes in functional MRI scans in these areas as research subjects engage in religious meditation. They reason that if thinking about God changes the way the brain works, there must be some inherent neural imperative to believe in God in the first place. In making this connection, neurotheologians are following the lead of neuroscientists who claim that changes seen in functional brain scans in persons who are happy, depressed, or obsessed demonstrate that these phenomena are brain driven.

Ilia Delio, who is a member of the Roman Catholic Franciscan Order and holds doctoral degrees in pharmacology and historical theology, gives this account of how neurotheologians conflate theology and neuroscience to make the case for a religious neural substrate. "It is tempting to speculate that there is a 'God module' in the brain and that such a module is located in the area of the limbic system; however, such speculation needs to be made cautiously. What these findings do point to, however, is that spirituality involves the brain. For the first time in human history we are beginning to understand spiritual experience not as something apart from the physical human but rather bound up with human matter, that is, the matter of the brain. Thus, matter and spirit are no longer seen to be opposed but are indeed mutually related, if not one and the same."³

Challenging the idea that religious belief is rooted in any particular brain structure or function, David L. Smith, a Roman Catholic priest and clinical psychologist, asks: "If 'God neurons' or 'God neurotransmitters' actually exist in the brain, are they defective in the agnostic and absent in the atheist?"⁴ Implicitly, Smith is holding the neurotheologians to the same standard that neuroscientists would feel obligated to meet when proposing a connection between specific neurons and neurotransmitters and some behavioral phenomenon: these neurons and neurotransmitters must be shown to exist. No scientist or theologian has come forward to stake a clear-cut claim to "God neurons" and "God neurotransmitters." Smith concludes that neurotheology is "a pseudoscience cloaked in the mantle of Cartesian dualism."⁴

The following quote from an article published in Zygon, the official journal of neurotheology, typifies the kind of language and reasoning found in neurotheological texts. The authors are Eugene d'Aquili, MD (a psychiatrist) and Andrew Newberg, MD (a neurologist). "We must now turn to the normal functioning of 4 tertiary association areas and to their relation-ship to the limbic system. We postulate that these areas, under certain conditions, may be involved in the genesis of various mystical states, the sense of the divine, and the subjective experience of God."⁵

Meaning seems to be more toyed with than revealed here as language slips and slides. This is about as far as the arguments of the neurotheologians ever go, yet they proceed to their conclusions as if they have made their point.

God: The genetic imperative
Dean Hamer, PhD, a behavioral geneticist who has worked at the National Cancer Institute (NCI) and the NIH, took the neurotheologians' proposal that religious belief has a neural substrate another step and asked: Is God, in effect, embedded in our genes and, if so, which genes? If this were the case, it would mean that people are not only wired to believe in God but genetically programmed to do so as well.

Hamer's work is not about demonstrating the existence of God, which is the domain of religion, but about showing that spirituality is a real phenomenon that can be described and measured. Spirituality, as Hamer sees it, derives from genes, and religion from memes—the cultural counterpart of genes—ideas, values, or patterns of behavior that are passed from one generation to another nongenetically, often by imitation. Religion, he believes, is rooted in nurture and spirituality in nature.

In 2004, Hamer published The God Gene: How Faith Is Hardwired Into Our Genes,⁶ which was showcased in a Time cover story on neurotheology.⁷ Hamer made it clear that he had approached his work with the tools of natural science: "The first task for any scientist attempting to link genetics to spirituality is to show that spirituality can be defined and quantified." (This quote and subsequent quotes by Hamer are from The God Gene.)

But how does one quantify spirituality, a quality that would seem by its very nature to defy measurement? As part of a study on genetics and personality in cigarette smokers sponsored by the NCI,⁸ Hamer had previously used the Temperament and Character Inventory, which includes a self-transcendence scale developed by C. Robert Cloninger, MD,⁹ professor of psychiatry at Washington University Medical School in St Louis. Hamer felt that Cloninger's self-transcendence scale made it possible to quantify "people's capacity to reach out beyond themselves—to see everything in the world as part of one great totality."