One church in the city of Slovyansk north of here, the Good News Church, has opened a school specifically to train missionaries for work in this conflict zone. So far, about 75 people have completed the one-month course and deployed along the 300-mile front. It is a spiritual turning of the tables, of sorts. When pro-Russian rebels held Slovyansk, they arrested and drove out evangelicals. Then the city changed hands, and the missionaries found their way back.

MARYINKA, Ukraine — On a recent frosty morning, a group of evangelical missionaries piled out of a Volkswagen minivan to meet elderly and poor people who had gathered on a roadside here. They handed out loaves of bread and Bibles, declaring, “Jesus wants peace!”

In the distance, the fighting that had been rattling along the front all morning picked up. A pastor, Yevgeny M. Medvedev, raised his hands and said, “Let us pray.”

By the time he had wrapped up the Lord’s Prayer, loud explosions were echoing through the town. “Deliver us from evil,” he said, finishing with an “amen” just as a shell exploded in the distance.

Maryinka, a Ukrainian-held town of apartment blocks and one-story homes outside the rebel capital of Donetsk, has become a hot spot not only for fighting, but also for saving souls.

As Ukrainian forces and Russian-backed separatists carry on an almost forgotten fight in half-deserted towns like this one, despite a year-old cease-fire, several well-organized evangelical groups are staging a campaign of their own. Based on their accounts and evidence seen here, they are finding fertile ground for their efforts.

Maryinka lies in what Ukrainians call the “gray zone,” between or close to the positions of government troops and Russian-backed rebels. While virtually everyone in eastern Ukraine has suffered in the nearly two years of war, residents of these areas have endured even more hardship.

About 6,000 civilians, including 350 children, remain in Maryinka, about half of the prewar population. Two schools remain open, though kindergartens, not much in demand in a place where nobody works, have closed.

In places, it is a town of bombed-out houses and overgrown yards, where people shuffle quickly across streets exposed to the high-powered sniper rifles of the separatists on the outskirts.

Like many towns along the line of contact between Russian-backed rebels and Ukrainian forces, Maryinka is without natural gas or hot water, because it is too dangerous for municipal workers to fix the holes torn in the pipes by shelling.

People in such places follow a glum routine of hauling firewood, waiting in lines for handouts of bread and groceries, and sleeping in root cellars.

The Ukrainian soldiers, bivouacked on the edge of town, are not much better off. In their dugouts, rough-hewed logs heaped with dirt form the roofs and discarded packing crates keep boots off the muddy floor. Clothes hang drying from nails on the wall.

There is sporadic fighting during the day, when monitors with the Organization for Security and Cooperation in Europe roam in armored white S.U.V.s. Only after they leave at 6 p.m. does the heavy mortar fire begin, said Lt. Col. Mikhailo M. Prokopiv, the Ukrainian commander in the town.

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