YUMA, Ariz. — The Rev. Victor Venalonzo opened his New Testament to the Book of Revelation on a recent Sunday and offered the men and women assembled at Iglesia Betania for a weekly Bible study a fresh look at its apocalyptic message.

“We’re failing as stewards of God’s creation, but these changes we’re seeing, that’s not God punishing us — we’re destroying ourselves,” Mr. Venalonzo told them. He alternated between English and Spanish, as he does all day in his Pentecostal church, which sits across from a trailer park and a half-mile from the Mexican border, serving Latinos who have recently arrived in the country and those born in the United States.

Until recently, the environment was never a topic that Mr. Venalonzo included in sermons to his congregants, who are mostly concerned about how they will pay their bills, find work, and keep their children on course in school and away from drugs.

But that has changed as development, drought, overuse and a drier, warming climate threaten the Colorado River, the source of the water they drink and use to irrigate the fields where they work. “Our lifeblood,” Mr. Venalonzo calls it.

From the Rockies all the way to this arid corner of southwestern Arizona, he and other Hispanic evangelical pastors have begun to preach a gospel of salvation for the struggling Colorado, framing the 1,450-mile river as a gift from God that the Bible commands them to protect.

Once a mighty waterway, the river has been reduced to a trickle in some parts, undermining the survival of a rapidly growing region that is home to a third of the Latinos in the United States. The pastors, who connected through word of mouth and informal networks organized around a shared Christian belief in being stewards of the earth, are packing their sermons with conservation tips: Take quick showers, use carwashes that recycle their water, and if you visit the river, do not leave any trash behind.

These are not the tree-hugging types who are typically the face of the environmental movement. They are men and women in elegant Sunday wear, deployed in a divine mission that is as much about education as it is activism.

“We have to nourish our spirit and our bodies, and where does our food come from? From the land,” said the Rev. Helia Martinez of Templo Cristiano Vino Nuevo, a church that occupies several storefronts in a tiny commercial center past an expanse of sprouting wheat in the nearby city of San Luis.

“If there is no river, there is no water,” he added. “If there is no water, there is no farming, no food, no work. There is no future.”

Although some non-Latino evangelicals have been engaged in the conservation movement for more than a decade, this is new territory for Hispanic pastors — and those who are part of it say they still have a lot of convincing to do among their peers.

Juan Manuel Almanza, who leads a multinational Spanish-speaking church called Centro de Adoración Familiar in Henderson, Nev., said his colleagues often asked, “Why are pastors spending time on this?”

It is about claiming the role of the church as a force for community transformation, he said. Others say it is also about giving a voice to new immigrants unfamiliar with the workings of American political participation, and encouraging second- and third-generation Latinos to take action.

“This is about creating a sense of responsibility: What are we doing to the land, to the animal life here, when we’re just trashing it?” said Dennis Rivera, a longtime pastor in Colorado who will soon take over as director of Hispanic relations for the Assemblies of God, the world’s largest Pentecostal denomination.

Noah Toly, a professor of politics and international relations at Wheaton College, a Christian school in Illinois, sees it as a harbinger of the rising power of Latinos in shaping the evangelical agenda. The lead role taken by low-income Hispanic congregations also helps dispel the widespread assumption that environmental issues are “luxury causes” reserved for the rich and white, he said.

Maite Arce, founder of the nonprofit Hispanic Access Foundation, has been helping organize the pastors, who have started a networking group of their own: Por la Creación, or “for the creation.” They are working together to “build a cohesive narrative” between the lives of their congregants and the environment, and one way to do that, Ms. Arce said, is to explain the effects that, say, dirty air and contaminated water have on health.

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The Trump administration has proposed a 31 percent cut to the budget of the Environmental Protection Agency, adding a tinge of politics to advocacy that the pastors insist is rooted in religion.

Their embrace of the environment began as individual discoveries. One of them took congregants on their first trip to the Rocky Mountains to show them where the water they drink at home comes from. From a traveling minister passing by San Luis, Ms. Martinez became aware of the connection between the health of the Colorado River and the livelihood of agricultural workers who, on Sundays, fill her pews.

For Mr. Venalonzo, frequent trips to Israel opened his eyes to the challenges and risks that a disappearing body of water can bring to a region’s stability.

He thought of the four rivers mentioned in the Book of Genesis and how only two of them, the Tigris and Euphrates, exist these days. Then he remembered the Colorado down the street, marking the line between the United States and Mexico, where it dries up well before its terminus in the Sea of Cortez.

American Rivers, a conservation group, recently placed the lower Colorado River at the top of its annual list of the most endangered rivers, in part because of climate change, which has brought less precipitation and caused more water to evaporate from Lake Mead, a reservoir already at 41 percent of capacity. Another reason is that the demands for river water are outstripping the supply in three of the seven Western states served by the Colorado and its tributaries.

Mr. Venalonzo used to hold baptisms in the Colorado, but it was so shallow three years ago that church members had to sit on its bottom to be fully immersed. Since then, the baptisms have been held at the church.

“I have a granddaughter,” he said, “and I don’t want her to say, ‘There used to be a river there,’ when she grows up.”