It was shown in all Western countries that religiosity is a frequent phenomenon, even in the Netherlands (one of the most secularized countries in the world).5 Religiosity is expressed in many different beliefs, in different ways—as an omnipotent personal god, an abstract principle, an afterlife, immortality of the soul, divine influence in one’s life. Although church and church authorities have lost prestige, religiosity still has a strong appeal.
When data indicate the high prevalence of religiosity in community populations, reason is violated when it is considered as abnormal, primitive, regressive, or atavistic. Religiosity is a normal component of the human personality—it is an attribute of the human mind, whereas religion is a product of the human mind. Religion can be disposed of; religiosity is there to stay.
The second set of data indicating that religiosity is a normal constituent of the human personality is biological in nature.6 Religiosity, although partly learned, is in part genetically anchored.7 Moreover, there is evidence that the brain contains neural systems that are at the root of spirituality. If these neural systems are activated by electromagnetic currents, religious experiences occur in both believers and nonbelievers. During intense religious preoccupation (as in praying and during mystic experiences), blood flow and glucose consumption in these regions are increased. These are signs of increased neuronal activity.8
Furthermore, the intensity of religious devotion and its salience for a given individual have been found to correlate with the binding capacity of certain serotonin receptors.9 Does that mean that religiosity is biologically caused, that it is no more than the product of some overactive neuronal circuits? No, the brain is the intermediary between religious needs and the gratification of those needs. The religious needs are, as discussed, of psychological origin; their gratification is made possible by the brain through biological processes.
By way of an analogy: one is moved by beautiful music. That feeling depends on still largely unknown brain circuits that generate aesthetic experiences. Without these brain circuits, aesthetic experiences would not occur. However, the circuits are not the cause of those experiences, the music is. Neural circuits make the experiences possible. The brain is the intermediary between the music and the sense of beauty one experiences. The same holds for religious experiences. Their origin is found in psychological needs; their gratification depends on brain activation. The brain is the intermediary between need and gratification of those needs.
The fact that religiosity is biologically based indicates that, evolutionarily speaking, religiosity provides functions advantageous to mankind. I hypothesize the main advantage to be its illuminating potential.
Psychiatry provides further support for the thesis that religiosity may enlighten a life.10 Koenig reports on the relationship between religiosity and depression. The faithful were compared with nonbelievers. The study findings indicate that under comparable, taxing circumstances, the risk of depression is smaller among believers than among nonbelievers. If depressive symptoms did appear, recovery was faster among believers than among nonbelievers. The same held true for long-term prognosis.
However, there is an important caveat: the beneficial effects of religiosity were demonstrable only in those with a positive image of God—God experienced as a support system and as a source of hope, a source of positive expectations and, if so needed, as a source of consolation. There are indications that God as a demanding, punishing, guilt-inducing authority has an opposite effect and increases the risk of depression and negative outcomes.11