"If we are really going to look at this powerful force in human history of religion and spirituality, I think we really have to take a look at how that affects our brain -- what's changing or turning on and off in our brain," Newberg said.
When asked if he was skeptical about what he'd find when he decided to study the brain at the moment someone is speaking in tongues, Newberg said, "If … the question is, is this a real phenomenon? Is this really the voice of God speaking through them? That's a much more problematic question, I think, and something that I'm not sure if we have specifically answered just by doing our study."
Newberg used CT scans to look at what happens in the brain's control center when someone speaks in tongues.
Study particpants like Donna Morgan listened to gospel music during the first scan. Brain activity during that scan was then compared with brain activity as the subject spoke in tongues.
Morgan was excited when she heard about the study. She was convinced that the results would support what she said she feels all the time.
"When I heard about the study, I already knew, in my spirit, that it was going to be proven that there was a part of our brain that we have no control [over]," she said, "that when the Holy Ghost is interceding for us we are out of control."
Newberg has been studying how faith is mapped on the brain for quite some time. He's recently published a book called "Why We Believe What We Believe."
In earlier studies, he looked at what happens in the brains of Buddhist monks meditating and Franciscan nuns praying. The results were quite different from what happens in the brains of people speaking in tongues, whose brains, he found, went quiet in the frontal lobe -- the part of the brain right behind the forehead that's considered the brain's control center.
"When they are actually engaged in this whole very intense spiritual practice … their frontal lobes tend to go down in activity. … It is very consistent with the kind of experience they have, because they say that they're not in charge. [They say] it's the voice of God, it's the spirit of God that is moving through them," said Newberg.
"Whatever is coming out of their mouth is not what they are purposefully or willfully trying to do. And that's in fairly stark contrast to the people who are -- like the Buddhist and Franciscan nuns -- in prayer, because they are very intensely focused and in those individuals the frontal lobes actually increase activity."
We asked Stoltzfoos to visit the University of Pennsylvania to have his brain scanned by Newberg while he spoke in tongues, and Stoltzfoos did not hesitate in agreeing to participate.
"I don't think faith has anything to be afraid of from science. Science validates faith, so bring it on, whatever the facts are, bring it on."
First, Stoltzfoos' brain was scanned as he prayed in English. Then, on Newberg's cue, he spoke in tongues, which sounded like a foreign language -- a little Hebrew, a bit of German -- but actually he wasn't saying anything in any known language.
Newberg said the scan showed that part of Stoltzfoos' frontal lobe did go quiet.
But what science determines at the end of the day is of no consequence to those who believe they are blessed with the gift of tongues.
"When you have experienced this, you don't really care what anybody else thinks. It is personal in the first place; it is something between you and God," said Stoltzfoos. "So we don't really care if it is validated or not, but it is fascinating when it is, so that people who have thought we are crazy can have something to look at and -- we are still crazy, we are just not as crazy as they thought."