In the Christian tradition (among others), the human soul is an immaterial entity that comprises the essenceof our true selves and is capable of union with the divine. Given this understanding, it is the soul which seeks to know God, and not the physical brain. However, modern science shows this belief to be false. In fact, the drive to be religious and spiritual has been demonstrated to be the result of biology, not an immeasurable and unknowable essence akin to a soul.
There have been numerous studies, conducted in multiple countries, on twins which have clearly demonstrated the genetic propensity for religiosity. While environmental factors do contribute to the phenomenon, these studies controlled for their effects by looking at adopted twins who were raised apart as well as comparing the differences between fraternal and identical twins. Based on the results from these studies, scientists have determined there is a 40-50% genetic component to religiosity.
The God Gene(s)
While there is a clear connection between genetics and religiosity, scientists have yet to understand all the specific genes that lead to this predisposition. In his 2005 book "The God Gene: How Faith is Hardwired into Our Genes" geneticist Dean Hamer argued the VMAT2 gene played a central role in the phenomenon. VMAT2 is involved in regulating the hormone dopamine, which produces the positive emotions accompanying mystical experiences. However, dopamine is excreted during more than just mystical experiences, and other scientists have argued its effect on overall religiosity is very minor.
Fortunately, there is some promise in the DRD4 gene, which affects people's susceptibility to environmental influences. In one study, students were more willing to volunteer for organizations around campus when primed with religious messages. However, being primed with these messages had the opposite effect on students with a particular variant of the DRD4 gene. Thus, while it may not make people religious per se, it may play a role in their ability to be influenced by religious institutions.
Theory of Mind
Recent research suggests that people with a stronger capacity for theory of mind tend to have higher levels of religiosity. According to psychologist Simon Baron-Cohen, theory of mind can be described as the ability to "infer the full range of mental states (beliefs, desires, intentions, imagination, emotions, etc.) that cause action. In brief, having a theory of mind is to be able to reflect on the contents of one's own and other's minds." This connection between religiosity and theory of mind seems to be in line with the research conducted by Tanya Luhrmann, as described in my previous post. In her studies, she discovered that experiencing "God" had a great deal to do with people's capacity to imagine interactions with him. She also noticed that while practice plays a key role in the ability to have these experiences, there were some people who were incapable of having them despite their best efforts in training their minds. Tanya's findings were also supported by another study which demonstrated that religious thoughts occur in areas of the brain associated with theory of mind.
One interesting result of this relationship between theory of mind and religiosity is that women in general tend to have both higher rates of religiosity and theory of mind. Conversely, people with autism have severely diminished capacities for theory of mind and they are more likely to be atheists than the general population.
Temporal Lobe Epilepsy
The temporal lobes of the brain are involved in auditory perception, memory, speech, emotional responses, and visual perception. About 4% of those who have temporal lobe epilepsy experience religious-oriented auditory and/or visual hallucinations. Some also experience a personality change called the Geschwind Syndrome, which is characterized by excessive speaking and writing, a reduction in sexual interest, hyper-religiosity, hyper-morality, and deepened cognitive and emotional responses. In ancient cultures, sufferers of epilepsy were believed to be possessed by demons or blessed with divine messages and visions. Some psychiatrists believe Paul the Apostle suffered from temporal lobe epilepsy, which would account for his religious visions, fervent religiosity, frequent speaking and writing, and his many rules regarding sexual conduct. In fact, modern scholars weren't the first to make this connection, as the old Irish name for epilepsy was "St. Paul's Disease."
Many Christians believe we are all programmed to seek a relationship with God. This, according to their perspective, is why there are so many religions. In addition, the traditional Christian view is that people who do not follow the teachings of Jesus will spend eternity in hellfire. Conversely, those who are the most fervently religious/spiritual are paragons of faith, and an example for the rest of humanity to follow. However, evidence suggests people are predisposed to be more or less religious. Thus, the extent to which people seek God is not necessarily their choice. It is merely the luck of the draw. If the traditional Christian view is correct, and non-believers are going to Hell, it was ultimately God's choice from the very beginning.
Good article about twin studies and religiosity
Good article on spirituality and temporal lobe epilepsy
Good article about theory of mind and female religiosity
Great video on temporal lobe epilepsy