After Harvey Stranske sank a sandpoint filter in the clay-red river flowing near Wadega, he pumped water into a garden by the riverbank. It ran clear and clean enough to drink. Nearby, a Jumjum woman drank in his feat. "Mister," she finally declared, "you are God."

That was 1949, and even though white men and women had been taking up missionary posts in this part of Sudan for a decade, locals still looked upon them as miracle workers. Most of southern Sudan, and particularly the Blue Nile region near Ethiopia, remained isolated even through the era of British control.

Harvey and Evadene Stranske were alone the first year they opened Wadega station for Sudan Interior Mission. It was the mission's fourth of five stations set up to evangelize local tribes. The Stranskes and their three small children lived for a time outdoors under a wild fig tree. Jumjum women would stop by to pat Mrs. Stranske's white face, murmuring, "Ana, ana, ana"-a tribal expression for surprise.

Plentiful work helped to bridge the cultural divide. Locals in Wadega fired bricks to build houses for the Stranskes and newly arrived missionary Bill Rogers. Eventually they helped to construct a church, a clinic, and a small school. They cleared and leveled ground for an airstrip. Mr. Stranske surprised his neighbors by planting and sharing mango, grapefruit, guava, and papaya trees. Later, Mr. Rogers added three rows of banana trees.

It was harder to narrow the spiritual gap. The missionaries at Wadega and nearby Mayak encountered fierce opposition from Islamic authorities and witch doctors. Missionaries at Chali station to the south quickly learned that twins born in the Uduk tribe were buried alive because they were thought to be a curse. The tribes had no written language. Mission workers spent years reducing the language to writing before they could begin Bible translation. Chali missionary Betty Cridland used up her first furlough researching the suitable Uduk term for "holy spirit." Without Scripture, they taught by hymns and simplified Bible stories. Converts came slowly: In 10 years at Wadega, the Stranskes had fewer than 10 new Christians. The Chali station was underway for two years before holding its first baptism. Even that slow start came to an end when Sudan's Islamic government began expelling missionaries, less than 10 years after independence from the British.

When the five Sudan Interior Mission stations closed by government order in 1964, their work in the region officially ended. Traces of their physical existence have nearly vanished. Buildings were bombed or dismantled by the Islamic regime. Gardens and wells fell into ruin. Airstrips went to washboard.

While the outward signs of the mission work wasted away, spiritual development was rapid. Forty churches dot the region today, with a churchgoing population of 10,000-15,000. They call themselves collectively Sudan Interior Churches in deference to the missionary legacy. Churches have reopened on four of the five former mission sites. One station, Doro, remains in the hands of the Islamic government. Church leaders range from pre-civil war converts like Michael Yerko in Wadega and Timothy Nyero in Kurmuk, to twentysomethings who grew up in Ethiopian refugee camps and learned doctrine from Sudan Interior Mission workers there.

"SIM planted a huge amount of seed and we are watering the church that has grown up there," says Blue Nile Project director Dennis Bennett. "It is a supporting role. The churches have taken the responsibility to evangelize their own neighbors."

With mission groups out, relief groups have to come alongside the church cautiously. Blue Nile Project, along with Safe Harbor and Voice of the Martyrs, takes humanitarian assistance to the whole community-and that often means Muslim authorities-before directing Bibles and pastoral training just to the churches. Blue Nile Project is working with Sudan Interior Mission to resurrect tribal translations made by its missionaries in the 1940s and 1950s. Already it has made New Testaments available in those languages. Director Dennis Bennett hopes to deliver texts of Genesis and Exodus early next year.

The legacy would be a footnote were it not for the missionaries' tough-mindedness. Mary Beam, who for several years headed up the Chali station with Miss Cridland, was known to climb into rafters in search of errant schoolboys and haul them back to the classroom. When she learned that witch doctors were conjuring against her, she confronted them directly. Several later became Christians.

That boldness was passed on to Sudanese church leaders. When the missionaries were expelled, the new Christians were under heavy pressure to send their sons to Islamic schools. The leaders exhorted them not only to resist, but to adopt Christian forenames as a sign of defiance. That stubborn rebellion is surviving decades of persecution and war. At a recent church dedication service, Kurmuk's Pastor Timothy challenged members to continue evangelizing Muslims. "My heart is water to see [the Muslims], going through town, refusing to believe that Jesus is the son of God," he told them.