According to Pastor Tim Keller, following his patron saint C.S. Lewis, being a practicing member of a religion is distinct from being a true believer. We can understand this from a theological point of view, but can belief be scientifically observed, or even measured?
A growing number of neuroscientists have taken up with question, with the ambitious goal of measuring what happens to the human brain during spiritual experiences.
To measure the effects of trance states and ritual on the brain, scientists use a technique called single photon emission computed tomography, in which subjects are injected with a chemical that emits gamma rays. A computer collects the information transmitted by the rays and constructs from it an image of the brain depicting blood flow to the various regions. The more blood flow to a particular region, the more brain activity.