Here is the only light amid the Sunday-night darkness of the plains, its yellow glow visible for a mile around. People travel here down two-lane roads, past flags that snap in the wind and a sign that reads “Only God Can Save America.” They park in front of the steeple at the corner of Center and Main. Pastor Fred Greening greets them at the door.

Theirs is a church of 400 in a town of 600, where four generations stand together to bow their heads in prayer. Cowboys wear boots and roughnecks wear flannel. A 9-year-old sets down his toy truck and clasps his hands. Together they recite pledges of allegiance to the United States, to the Bible and to the Christian flag.

“May God guide us and watch over us,” an assistant pastor says. “May He work to preserve our community and the values we hold dear.”

Oklahoma will hold its Republican primary on Super Tuesday, bringing the cultural debate over the heart of conservatism to the conservative heartland. The presidential campaign has turned into an argument about values and faith — a battle long underway on the prairie of central Oklahoma. Here, they fight to protect their town from what Pastor Greening calls the “slow and steady decay of moral America”: the erosion of traditional marriage; the methamphetamine addicts content to rely on public assistance; the political correctness creeping ever south from the college in nearby Norman, which they fear will force God out of their government offices and schools.

Now more than ever, they want a politician in that Washington who will safeguard the culture of this one.

Four years after an election defined by Hope and Change, Oklahoma remains a place that mostly hopes not to change. All 77 counties in the state voted for the Republican candidate in each of the past two presidential elections. Even as every other state in the country became more liberal or more conservative, the politics of Oklahoma stood still: Exactly 65.6 percent of people here voted for President George W. Bush in 2004, and exactly 65.6 percent voted for Sen. John McCain in 2008.

Change also has been forestalled here in Washington, a grid of single-story houses surrounded by wheat fields and flood plains. The cotton gin and feed mill still frame Main Street, and decades-old graffiti still cover the water tower. A few dozen men still gather each morning at the American Legion to play dominos, crack peanuts and spit tobacco juice on the floor. The same “In God We Trust” posters still hang at the public high school, which serves the same pizza pockets on Mondays and throws the same Christmas party that is never called a holiday party, and where no extracurricular events are scheduled on Wednesdays or Sundays because those days are reserved for church.

On this Sunday night, Pastor Greening talks to congregants about what he calls his “big deal” topics: the sanctity of marriage, the war on Christianity and the threat of sharia law. He moved here from Chicago a decade ago because he wanted to live “someplace more principled and simple, where people aren’t afraid to talk about the 900-pound gorillas in the room.” Now he delivers roses to the state Capitol each year to representatives who oppose abortion, and he leads annual service trips to Central America. He has grown the church property from one acre to 11 and built a campus with gym space and classrooms.

“I’ve found a very receptive congregation,” he says, “a place that has a common purpose.”

Everyone here is living a version of the conservative life. Each is fighting to preserve the sanctity of this place.

Pastor Greening offers a final prayer. “May the Lord bring you courage and strength,” he tells them, and the congregants file out of the church.

* * *

One of them is Mark Tague, 44, who wakes the next morning to the same routine that has grounded his family for 100 years. It’s calving season, and he heads out to his 160 acres of yellowed grass and sienna dirt to check on the herd. He drives a white Ford pickup with the high school logo affixed to the bumper. His 5-year-old daughter, Lily, sits in the back seat. They pull up to a newborn calf, only a few minutes old, and roll down the window to watch it take its first steps.

“Good gravy, he’s looking good, isn’t he, Lily?” he says.

“I like him,” she says.

Tague went away to college after high school, got a job in finance and lived in St. Louis for a few years, but he moved home to Washington as soon as his company told him he could work remotely. His ancestors, Chickasaw Indians, were forced to Oklahoma on the Trail of Tears in the 1830s, and they eventually built barns and a bank and turned the town into a railroad stop. His great-grandparents donated land to build the Washington schools, and his grandparents were part of the first graduating class. His mother went there. His three children go there now.

“I want my kids to grow up with values and ways of life that I had and my parents had,” he says, so his youngest son tools around the garage on a Big Wheel, and his oldest daughter keeps her riding horse at the family barn built in 1907, and they buy their drinking milk from Braun’s because he always has. “Why look for change?” he says. “I like to know that what you see is what you get.”

What you see is Sid’s Easy Shop opening downtown each morning at 6, where Sid will sell you gas, rent you a movie, make you a new set of keys or bring your soda to one of the classic red booths preserved from the 1950s. The post office, its roof painted red and white to reflect the stripes of the American flag, opens for business a few hours later. Next door to that, Casey operates her coffee shop with the help of her husband and five kids, who take turns working the register, Yes Sir and Yes Ma’am, and sell T-shirts imprinted with the phrase “Make God Famous.”

What you see is a parade of several dozen well-wishers lining the street and stretching out their hands to the bus every time one of the varsity high school teams leaves to play a road game, and a few hundred people gathering for community workdays to fix up the Little League field so Washington doesn’t waste money on parks and rec. Almost all of the houses in town are single-story ranchers, and more than 70 percent belong to married couples — few Hispanic, fewer black, none Muslim and none openly gay.

What you see are calves dropping in the spring, coyotes circling at night, shooting stars, roaring tornados and thick flocks of birds migrating across skies that round over the horizon.

“Is there anyplace else?” Tague wonders.

He looks more like a financier than a farmer, with wire-rimmed glasses, close-cropped hair and an iPhone he uses to check the per-pound prices for live cattle. He still travels every few weeks to Indianapolis or St. Louis for his job at a thriving mortgage industry start-up, but he dreams of expanding his herd and raising cattle full time.

If he can’t do it, maybe his children will.

“You want this place, Lily?” he asks.

She smiles and nods.

“Good,” he says, “ ’cause I’m going to make sure you get it.”

* * *

Another of Pastor Greening’s congregants wakes a day later in the house she constructed with her husband and three children outside of town, where there is fresh venison in the refrigerator and four horses grazing outside. Lisa Billy, 45, grew up nearby in the small town of Purcell, where she shook pecan trees, hauled hay and cared for pigs and horses. She watches “Andy Griffith” reruns. She prefers to wear a U.S. Marines baseball cap and cowboy boots stitched with the Holy Cross. “I am rural Oklahoma,” she says.

But, on this day, she dresses in a business suit, puts in hoop earrings, grabs her Bible and heads north. She drives an hour on the freeway to Oklahoma City, straight into the culture war.

Billy is the state legislator elected to defend the values of this place — her values. She is the granddaughter of a Golden Gloves boxer, a petite woman with intense eyes and high cheekbones who volunteers to carry most abortion bills through the House and who local antiabortion groups herald as “fearless.” But, lately, she has been receiving a few hundred hateful e-mails about her newest piece of legislation: a “personhood” bill that would give rights to a fetus from the moment of conception. So vicious are some of the e-mails that she has asked her 17-year-old son to accompany her at night for protection.

She calls an assistant pastor on her way to Oklahoma City for spiritual advice and receives text messages from the supporters she regards as her “prayer warriors.” She parks near the Capitol, where protesters have assembled outside. Her bill won’t be voted on for weeks, but protesters come daily. Billy walks into her office and closes the door. She calls her assistant into the room. “Pray with me,” she says.

The walls of the office are decorated with a certificate of recognition from Americans United for Life, with a Call to Prayer for Oklahomans, with a list of 30 Ways to Pray for People in Authority. The Bible and the House Rulebook are stacked at the center of her desk. “Those are the two things that guide me here,” she says, “and the primary one is the word of God.”

Outside her window, more than 300 people gather on the Capitol steps to protest the personhood bill. Women dress in costume, wearing aprons and carrying rolling pins to mimic a place that seems stuck in another time. One speaker yells: “Welcome to Oklahoma. Now turn your clock back 50 years.” Another follows: “Religion doesn’t belong in my ovaries or my Congress.”

Meanwhile, Billy and her assistant walk upstairs to the Capitol’s weekly devotional luncheon. Billy takes her seat at the head of the table and stands to speak. “It’s nice to be surrounded by other believers,” she says. One pastor prays over lunch, another prays for the legislators, and then Billy asks if she can pray for the pastors.

“Thank you for allowing us to gather and share in your wisdom, Lord,” she says, eyes closed, head bowed, voice rhythmic. “We know it’s a challenge when we’re standing in the middle of a trial. Let us be calm under fire in the spirit of Jesus.”

She leaves the Capitol an hour later for another meeting. She drives past the protesters, past the skyscrapers of downtown, past the bars surrounding the University of Oklahoma, past the roadside casino with its flashing marquee advertising “good action and generous slots.” She exits the freeway and turns onto a two-lane road, winding her way back toward the familiarity of Washington.

* * *

Where, the next morning, a Wednesday, Sid opens at 6. A dozen men show up at the Legion to play dominos at 7. The kids at school recite the Pledge of Allegiance at 8:30 and spend a moment in silent prayer.

A storm rolls across the sky. Flagpoles rattle in the wind.

Another day is happily the same.

Night falls, and one yellow light interrupts the darkness of the prairie. The congregants travel past the water tower and the feed mill and the cotton gin to the corner of Center and Main. Pastor Greening waits at the door.