Michael Egnor argues that the study of the neuroscience of mental states, including religious belief, is a reasonable pursuit but neurotheology, as a science, faces huge obstacles:
3. The most subtle and, I think, most dangerous consequence of neurotheology is its implicit endorsement of a sort of “prosperity gospel” in terms of making the brain “healthier.” The prosperity gospel is the teaching that belief in God and right conduct will bring you prosperity — wealth, health and happiness — in this life. Religious belief becomes a matter of self-improvement, a cerebral face lift. Neurotheology stamps a scientific imprimatur on the profoundly misguided doctrine that if you believe in God, if you observe the Sabbath, if you never fail to pray your rosary, your brain is better! Your frontal lobes get better blood flow, your hypothalamic neurotransmitters are better balanced, and your cerebellum is more finely tuned! But for what?
Faith in God — genuine faith — is faith in Truth. In the Christian perspective (with which I am most acquainted) we are created to know and love God and to enjoy him in intimate friendship for eternity. There are no promises about more robust cortical gyri and enhanced striatal dopamine.
Some of the most holy men and women have not exactly prospered neurologically — martyrdom tends to ablate, not augment, cerebral blood flow. St. Peter’s brain worked no better when he was crucified upside down for his Lord and St. Paul’s worked no better when he was beheaded for the Faith. St Theresa of Avila and St. John of the Cross (pictured) had agonizing dark nights of the soul. St. Francis of Assisi lost his health and shortened his life through his austerity, and St. Catherine of Siena probably starved herself to death.
Genuine religious faith and practice is a search for transcendent truth, not a program for brain health and emotional happiness.
Since Egnor mentioned the Christian perspective:
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God’s existence is proven by science. Arguments for God’s existence can be demonstrated by the ordinary method of scientific inference. If we approach the arguments logically, as the ancient philosophers did, we will see that it is more certain that God exists than that anything else does.