(Reuters) Standing in a church crypt lighted by a flickering light bulb, a veiled woman muttering Islamic prayers looks on as a Christian monk tries to exorcise a demon she says possesses her daughter.
Other black-robed exorcists shout into the ears of two groaning and vomiting women in another corner of the room.
Muslims and Christians gathered in the underground chamber have come to a festival in honor of a Christian saint to seek his help in banishing demons they believe are afflicting their relatives.
The monks at the church of St George, or Mar Girgis as the saint is known in Egypt, in Mit Damsis, 47 miles north of Cairo, are renowned in the predominantly Muslim country for driving demons away.
"It is well known God's power flows from their fingers," said the Muslim mother wearing a black headscarf and shawl, who would not give her name, as she watched the monks perform the exorcism on her half-conscious daughter.
Egypt's Muslim majority and roughly 10 percent Coptic Christian minority generally live and work together in harmony, although there have been cases of sectarian violence in the past.
Their history has been intertwined for more than a thousand years in Egypt, where they observe many of the same beliefs and traditions.
In Mit Damsis, both communities came together in a carnival atmosphere to honor the Christian saint.
Veneration of saints, part of the Coptic worship, is frowned upon by orthodox Muslim scholars. But like many other ancient traditions, it is widely practiced by Muslims in rural areas.
Some say such veneration pre-dates Islam and Christianity, and has roots in Egypt's ancient pharoanic religion. The practice, along with exorcisms, is often a central feature of rural religious festivals, known as mulids.
"Mulids to honor saints go back to pharaonic times when people worshiped one national god and a host of local gods," said Milad Hanna, a prominent Coptic writer and thinker.
In Christianity, Jesus was said to have driven demons from the possessed. Islam accepts the existence of demons, although scholars say demons are unable to take control of a human body.
Some, however, are skeptical about the practice of exorcism. Hanna said some of those believed to be possessed by demons might simply be suffering from medical conditions.
"Families could be dealing with a relative who in reality is suffering from schizophrenia or epilepsy. But they might think it's possession," he said.
Others attend the colorful mulids with little religious motivation.
"There are shooting galleries and lots of girls to talk to," said Ahmed, a Muslim teen-ager, as he wandered past a stall in Mit Damsis that sold Christian religious posters alongside portraits of Arab pop stars.
At other kiosks along the village street, traders shouted out prices for porcelain statues of Jesus and sportswear with counterfeit logos.
But for many Muslims and Christians in Mit Damsis, it is the power of St George which draws them to the celebration.
According to some traditions, the saint has a patchy reputation for promoting inter-faith tolerance.
One legend says St George, the patron saint of England, appeared to English troops and inspired them against Muslims during the Crusades.
Karel Innemee, visiting professor of Coptic culture at the American University in Cairo, said the saint's life was probably based on a Roman soldier who was tortured and killed for his Christianity in third century Asia Minor.
As a warrior, who according to other legends killed a dragon, St George's help is thought to be particularly powerful in exorcisms.
In Egypt, popular tradition says St George hailed from the north of the country. Some local Muslims believe the Islamic holy book, the Koran, makes veiled references to him as a holy man. Scholars say Christian traditions surrounding the saint seeped into the Muslim faith when it spread in Egypt after 640 AD.
Most exorcism ceremonies -- including those in Mit Damsis -- involve powerful imagery, which experts say appeals to many, particularly rural, believers in both faiths.
"The monks are large, imposing figures robed in black with big beards. They order the demon to leave the body. This has an effect on the people watching. They imagine it to be effective because it seems powerful," Hanna said.
For some Muslims, the dramatic Christian traditions offer more vivid images than their own customs. The Muslim ritual can often simply involve saying a prayer over the sufferer.
"It doesn't have the same impact on the people watching. They don't imagine it being as effective," Hanna said.
Outside the crypt of the church at Mit Damsis, more pilgrims were hoping for St George's help. One man leaned against the wall of the church nursing a swollen scab-covered leg.
"I know St George will cure me. He was tortured and understands pain," he said.