This is not the kind of place where a middle-class American family man like Ted Hesser would seem to fit in.

Thick tropical jungle surrounds bamboo and palm-leaf cabins here on a stagnant canal of the Caqueta River, 30 minutes by launch from the nearest, malaria-ridden town. The nearby settlers are mostly scattered groups of peasant colonists and native Indians, and the territory's most noted activities are cocaine smuggling and bloody guerrilla wars.

Hesser, in turn, is a 51-year-old man with a family of seven who looks and speaks the part of his past as a sober Pennsylvania science teacher with degrees from Harvard and Yale. "South America," he concedes, "would have been the last place I would have chosen to live."

And yet, Hesser and his family are now veteran residents of Colombia's wild southeastern frontier, along with 70 other Americans who have renounced modern culture and sometimes promising careers. Joined by more than 600 mostly Colombian colonists converted to a U.S. strain of charismatic Christianity, they have built an expansive network of farming communities that have become one of the region's most unusual--and controversial--religious missions.

Their motives and beliefs are poorly understood by local residents, and frightening rumors about what is called "the farm of the gringos" often circulate in the more distant towns. They have been accused of everything from Yankee imperialism and drug trafficking to exploiting local peasants and repeating the cult practices of Jonestown, the Guyana settlement that ended in mass suicide.

"We've had a lot of problems," said Blake Osburn, a blond 34-year-old Oregonian, "with people who can't understand why Americans would want to live out here."

But the residents of La Cocha, the headquarters of the seven Mission of Christ colonies in the department of Caqueta, insist their l5-year-old agricultural settlement is no more than a quiet refuge for fundamentalist Christians seeking the hard work and strict moral discipline of primitive religious communities.

Despite a series of disputes with disgruntled Colombian members, the mission has managed to survive the local rural violence and even win the favor of local military authorities.

"We have just found a place here," said Hesser, who packed his family into a Volkswagen camper 12 years ago and changed from teaching classes to tinkering with compost processes and soil fertility. "We have gotten away from dependence on city life and are living the way of most of the people in the world, with simple tools close to the land. I wouldn't move anywhere else."

So far the 460-acre farm at La Cocha, 60 miles south of the department capital of Florencia, remains far from its goal of becoming a rural agricultural model. It is not yet self-sufficient in food and its most advanced work is Hesser's hot composting operation.

Mission residents, in fact, seem less preoccupied with rapid development than with maintaining their distinctive community life style. "Our ideas have changed some and we have tried not to become isolated or to be segregationist," said Terry Kelly, a former Florida teacher and one of the founders of the colony. "But at the same time we don't want to mix with the outside world."

The foundation of the colonists' society is a strain of charismatic Christianity first developed in the early 1960s by Samuel Drew Fife, a former southern Baptist preacher who founded a church called the Miami Revival Center. Fife died in a plane crash in 1979, and according to members here, the group now has no central leadership, though another U.S. center in Bowen's Mill, Ga., serves as a center for annual conventions by affiliated but self-governing groups.

The sect is known as "charismatic" because it believes in direct communication between believers and God and a "baptism in the Holy Spirit" that manifests itself in the biblically cited gifts of speaking in tongues during worship, prophecy and faith healing.

While such fundamentalist Christian groups are not uncommon in the United States, Fife's movement was distinguished by the decision of many of its members to live in small, communal groups in wilderness areas with the aim of emulating early Christian societies.

The Colombian colonies, said Kelly, were created almost by happenstance. Returning from a visit to Christian missionaries in Peru in 1967, Kelly and seven other persons were arrested during a stopover in Florencia after police found a revolver in Kelly's luggage.

"While under detention, the Lord spoke to Sam and told him he should start a missionary center in South America," said Kelly, a tall, light-skinned blond with intense blue eyes. "Then the Lord told Sam that this was to be the place."

Later that year, Fife and Kelly returned to the jungle settlements outside of Florencia and persuaded a local landowner and fundamentalist Christian to rent the tract of land that is now La Cocha to the group for 30 years. Early in 1968, Kelly and three other Americans arrived on the property and began to build the farm.

Soon other Americans drawn to the wilderness began to arrive at La Cocha, including entire families, and the group decided to work and live communally, inviting local peasants and other Colombians to move onto the land and creating a self-perpetuating group of "elders" to manage the shared food, finances and land.

The Americans who came were largely conservative, fundamentalist Baptists who wished to escape modern U.S. society or raise and educate their children in their own way. Others, like Osburn, are younger dropouts from the counterculture movement of the 1960s or "reborn" Christians who wanted to spend time abroad.

"We all felt we needed to leave the city, the school system, to escape from the deteriorating conditions of government and society," said Kelly, one of the 16 elders who share authority at La Cocha.

Conditions on all the farms are austere. Members work long hours slashing jungle undergrowth with machetes or plowing gardens with teams of oxen, and live in simple bamboo cabins. There is no drinking and smoking, no long hair or beards, and no sports, and elders must be consulted about most important personal decisions, including marriage.

Some of the Americans have married other mission members since arriving, and young children who arrived with some of the first settlers have grown up, studied in schools built and run by the colonists, married, and begun their own families. In recent years the Colombian government has limited the number of foreign missionaries entering the country, and no Americans have moved to the farms from the United States since 1979.

While the American immigrants fuel most of the local suspicions, it is the Colombian members who have created the most controversy. Colombian journalists and observers have charged that the group is exploiting poor local peasants and farmers who, in some cases, have donated farms or other property to the mission.

Osburn, another elder at La Cocha, and other leaders argued that all the mission's members entered and can leave freely, and that many of the Colombians are not peasants but rural professionals who moved to the area to join the mission. Kelly said the property of ex-members has been returned when so requested.

Since the disputes over property and the scandal of Jonestown in 1978, the missions have also taken care to revise their membership procedures and quickly distinguish themselves to outsiders from the Guyana People's Temple.