Tales of divine intervention float out of local villages, telling of young girls who cry tears of blood, yogis who can lie in roaring fires, healers who can cure the sick with a single touch, Sufi shrines that ward off bad spirits, and Hindu holy men who live for decades without a single drop of water or crumb of food.
But are these miracles truly blessings from a higher being, or simply an elaborate magic trick to attract fame and followers?
One such proclaimed prophet, 82-year-old Prahlad Jani, lives in the state of Gujarata. He is a Swami -- or religious teacher -- who claims he hasn't had any food or water in more than 70 years.
"We examined him twice under close monitoring, once in 2003, another time in 2010," said Dr. Sakir Shah, Director of neuroscience at Sterling Hospital in Ahmedabad.
"We cannot say anything about his claim for 70 years, but during these ten days of 2003 and these 15 days during 2010, me, my colleagues, the team from defense institute very assertively confirmed that Mr. Prahlad Jani did not eat anything, did not drink, pass urine, did not pass stool," he said.
According to the U.S. Department of Health and Human Services, a person cannot survive more than 3 to 4 days without water, and not more than about a month without food.
"This is one of the most interesting, exciting experiences of my life," Shah said. "Scientifically, we have no explanation."
ABC News was granted access to the tiny temple high up in the village's hills where Jani practices, and the holy man talked about his mysterious abilities.
"My powers come from yoga and God," Jani said.
Describing himself as a living deity, Jani said that when he was 11 years old, a goddess touched his tongue to rid him of the need for food and water.
"People in India used to live 100 or 200 years but then came the influence of Western culture," he said. "Now the only exercise people get is with their remote controls."
On a tour of the "cave," as Jani called it -- actually a comfortable studio apartment -- "Nightline's" cameras caught sight of a working refrigerator. When asked about it, one of his minders immediately became defensive and said we could not look inside.
"No, only water to wash the mouth...no he didn't give permission to come in the room," the minder said.
It seemed strange for a man who doesn't eat or drink to keep a refrigerator in his room. But it didn't come as a surprise to Sanal Edamaruku, who is an outspoken atheist and head of the Indian Rationalists' Association.
Recently, Edamaruku had a confrontation on live TV with a Swami who claimed he could kill him by uttering mantras. Four hours later, Edamaruku was still alive and smiling.
"None of these people are holy because none of these people have any special capacity or any special thing," he said. "Most of these people who are claiming that they are miracle men or holy men or saints are con men, charlatans, exploiters."
Another example Edamaruku cited is Satya Sai Baba, a guru with millions of followers around the globe. He is most known for materializing jewelry and holy ash from thin air, but recent videos posted on YouTube showed his mystic abilities were just a slight of hand.