T.E. Lawrence called it “the finest castle in the world.” Paul Theroux described it as “the epitome of the dream castle of childhood fantasies of jousts and armor and pennants.”

Krak des Chevaliers overlooks the Homs Gap in Syria’s Al Ansariyah Mountains, near the border with Lebanon. Built in the 11th century by the Muslim emir of Aleppo, the castle was later rebuilt by the Knights Hospitaller, a European Catholic military order that wrested control of it and the surrounding area during the Crusades. For 150 years, European knights and their descendants inhabited the region, until the Muslim Mamluks chased them out in 1271.

The fortress is a lonely relic of Syria’s European Christian past. But the region it dominates, Wadi al Nasarah (Arabic for Valley of Christians), remains home to a flourishing Christian community rooted in the early church of Sts. Peter and Paul.

Though known for its support of Syria’s Christian minority, the Syrian government recently renamed the region, calling it Wadi al Nadarah, Arabic for the Green Valley. This subtle but essential variation in name, however, has altered little about the region. Most Syrians still refer to it as the Valley of Christians.

“There are about 40 villages in the area, most of which are Christian,” explains Carmen Nehme, a young woman from the settlement of Al Meshtayeh.

“One notable exception is Al Hosn, the village below Krak des Chevaliers, which is almost entirely Muslim,” she says, her long dark hair framing her chiseled face. Wearing jeans and a turtleneck, the 24–year–old Christian speaks fluent English and works at a local hotel popular with tour groups.

“We were traditionally farmers, harvesting our olives and growing grain crops and keeping animals. But these days, very few of us Christians are involved in that kind of work. We have prospered and have received a good education, going to university in the towns, so we either work in tourism or are professional people,” she continues.

Ms. Nehme’s generation is not the first to have left its rural roots: Her father is an electrician; her mother teaches at a local school.

Syria is a cradle of Christianity. The word Christian was first coined in the ancient Syrian city of Antioch — which has been a part of Turkey since the borders were redrawn in 1939. The apostles Peter and Paul settled there, nurturing a church that eventually emerged as the center of Christian thought in the eastern Mediterranean. Antiochene theologians, from both the Greek– and Syriac–speaking communities, played leading roles in the Christological controversies that eventually divided the early church, differences that are now understood as cultural and linguistic.

Even as masses of Arab Muslim troops invaded and conquered the Middle East in the seventh century, eventually receiving the majority of its population into Islam, Syrian Christians persevered, living peaceably with their Muslim neighbors.

Today, Christians make up about a tenth of Syria’s 22 million people. Half of these two million souls belong to the Orthodox Church of the Patriarchate of Antioch, the preeminent Christian institution in the country. As many as 500,000 people belong to the Syriac Orthodox Church, and another 125,000 belong to the Armenian Apostolic Church. Catholics number around 400,000 people and belong primarily to the Armenian and Melkite Greek Catholic churches.

The vast majority of the population of Wadi al Nasarah are Christian, 98 percent of whom belong to the Orthodox Church. The rest attend Melkite or Roman Catholic churches.

The region’s oldest extant Christian site, a sixth–century Orthodox monastery dedicated to St. George, is located near Al Meshtayeh and faces Krak des Chevaliers from the opposite side of the valley, three miles away.

The monastic foundation consists of several buildings, including two churches, and a cloistered courtyard. A newer church, built in 1857, houses an intricately carved wooden iconostasis that frames a rare collection of Arab icons. Across the courtyard stands a 13th–century church. Its vaulted apse, largely hidden behind a 300–year–old ebonized iconostasis, dates to the monastery’s foundation in the early Byzantine era.

In its heyday, the monastery served as one of the region’s major theological centers. Scores of monks once lived, prayed, studied and worked there, and its seminary trained the region’s priests. But dwindling enrollment forced the monastery to close its doors not long ago. Father Andrew, a priest in the nearby village of Amre, studied at St. George’s.

“We are sad that St. George’s is no longer a seminary,” says the priest, adding, “there is talk to start it up again. There is a convent in the nearby village of Marmarita, where students can study theology for three years and then go on to Lebanon to finish their studies.” But only three monks remain at St. George’s, which has become a favorite stop for bus loads of pilgrims and tourists.

“We get up at 5 a.m. to pray in the chapel and then do various chores like cleaning or working in the library, until breakfast at 8:30,” says Mar Christo, the monastery’s energetic abbot. Cloaked in his traditional black cassock, his woolly hat outlining his pointed beard and laughing eyes, he says that soon after breakfast, “the tourist buses start to arrive, so we show them around.

“Our two big feast days are Saint George’s Day on 6 May and the Triumph of the Cross on 14 September — plus of course Christmas and Easter,” he continues. “On feast days, many pilgrims come to stay at the monastery. A big market is set up outside selling icons and food. On Sundays, the villagers come to the liturgy, but not so many.”

Walking to the monastery’s kitchen garden, Mar Christo points to his beloved vegetables. “I love to do the gardening myself. There is no time I feel better than when I am watering the tomatoes and lettuce.

“We also have land belonging to the monastery that we farm,” he adds. “We do the work ourselves, but we also employ women to help with the hard labor and at harvest time.”

Similar to other rural areas in Syria, jobs are scarce in Wadi Al Nasarah, especially those suitable for its well–educated Christian youth.

Many leave the area to live in cities like Damascus, Aleppo or Homs,” says Ms. Nehme. “And then so many of us go abroad, to the United States or Australia,” she adds. “I have two uncles in Australia and my two sisters in Pennsylvania.”

The Sallom family from the village of Kilitia exemplifies the region’s migration patterns. On a sunny morning, the 76–year–old patriarch takes a break from gardening to chat. As he has done for the last 60 years, Hana Sallom tills his modest 12 acres, on which he cultivates corn, beans, vegetables and fruit.

“I have five boys and two girls. They all live in Homs, except one boy who helps on the farm. My wife used to farm, too, but she is sick in bed,” he says. “There have been many changes around here. Lots of people have left to take jobs in the army or government. Others travel to Homs every day to work and come back in the evening.”

The trend has many local Christian leaders concerned. “The problem here is that people are leaving, the population is going down,” says Father Andrew of Amre. “Christians started settling here in large numbers about five or six hundred years ago, but now gradually things are changing as people leave the area.

“These villages were Christian, but Muslims have started to move in. Many new apartment blocks have gone up, intended for Christians, but in five or ten years time there will be Muslims living in them.

“Mosques will get built,” he concludes, “and Wadi al Nasarah will never be the same again.”

Many of those who leave, however, return for the summer or during the Christmas season. And, looking out at the idyllic countryside, with its gently rolling hills painted in hues of olive green and gold, its ancient villages and stone churches, it is no wonder why so many natives faithfully return at least once a year.

One such émigré is Lamaan Nahas. On vacation, she is visiting her home village of Alkaimi with her aging mother and three children. Mrs. Nahas left Syria 17 years ago and now lives in San Francisco, California, with her husband, children and, for the past year, her mother. She loves San Francisco and her life there, she says, but she misses her home in the Valley of Christians. Her mother, her gray hair pulled in a bun, smiles broadly, visibly happy to be back home, even if for just a short stay.

As we talked, a couple of girls approached a nearby fountain fed by a natural spring with large plastic jugs brought from home. As they filled them with the fresh cool water, they giggled with delight. The valley has many natural springs and it is not uncommon for each village to have one nearby. Though all homes in the valley are equipped with modern plumbing and electricity, locals often prefer to collect their drinking water from these springs.

Despite the lack of opportunity, many of the region’s remaining residents are clearly happy to live in such a beautiful environment. Issam Abtehag and Sadaldeen Betrws, a couple from the village of Alkaimi, could not be happier. Both retired teachers, they live in a large house with all the modern amenities. A spacious balcony overlooks the village and its church and a nearby peach orchard. Yet, they understand their good fortune.

Climbing onto the roof, Mr. Abtehag points to a neighbor’s house, built of alternating rows of white and black stone, the traditional style of the region. But the once beautiful home languishes, unoccupied and in a state of disrepair. Visible signs of decay edge around the windows; weeds have taken over the walled garden. Mr. Abtehag says the owners left for North America long ago, abandoning the house to the elements.

Over mint tea and biscuits, the couple insists Christians are leaving Wadi al Nasarah mainly for better career opportunities.

“We have a nice house, clean air, safe water and good food. For Christians in Syria, life is generally very good. Indeed, we live better than most of the Muslims because we tend to be better educated and have good government jobs, or do well in business,” says Mr. Abtehag.

“In other countries of the regions, especially Iraq and Egypt, life has become intolerable for Christians and sometimes we worry what the future might bring,” he adds.

“Life here in Syria is very sweet!”

Sean Sprague is a frequent contributor to these pages.