Cowboys saddle up for ... church? Amen.

Snow has forced Ohio's Christian cowboys inside on an early spring day. Bull riders aren't the sort of people who complain about the elements, but there are certain drawbacks to setting up a church for cowboys in northeastern Ohio.

Pastor Royce Gregory, who tackled "1,800 pounds of mean" on the rodeo circuit for 17 years before turning his life to God, isn't worried about attendance. His pulpit, an engraved tan saddle perched on spindly metal legs, stands before a wooden cross ringed with a crown of thorns. It's a symbol, he says, of the simple message of faith that is turning cowboy churches like his into a national movement.

"A lot of pastors don't like me and don't like the idea of [the cowboy church]," Mr. Gregory says, referring to mainstream religious leaders in a part of the country not exactly lacking in places of worship. "But if you read the Bible, it is simple. It's only man that made church hard."

Such is the ethos of cowboy church, which is bringing come-as-you-are evangelical Christianity to the boots-and-Stetson set.

Faith and the Western way of life have long been linked. But in recent years cowboy churches have adopted a distinct identity – favoring riding arenas and barns instead of church buildings, carrying out baptisms in horse troughs, welcoming wranglers whose blue jeans are ripe with the smell of a working ranch – that has allowed them to grow faster than their founders thought possible.

In Texas, the epicenter of cowboy churchdom, the Baptist General Convention established its first cowboy church in 2000. By 2004, there were 21, and now there are 145, with 20,000 attendees each week, says Charles Higgs, the Texas Baptist group's director of Western heritage ministry.

Gregory's church, Life Brand Cowboy Church, belongs to the Cowboy Church Network of North America, which has overseen the launch of nearly 50 churches from Colorado to North Carolina in the past five years.

Jeff Smith, the network founder, remembers the moment the concept of the cowboy church crystallized.

No cowboy himself, he had rented a dirt-floor riding arena for the service. Cowboys lined the bleachers and Mr. Smith began preaching from the bed of a pickup truck. But something wasn't right. He jumped to the ground, holding his Bible and speaking of the Lord. Just him, the people, the dirt, the horses, and the Bible. He's started two other churches since.

"We're just on the front edge of this thing," Smith says. "It certainly isn't slowing down." In addition to cowboy churches, he has advised people wanting to set up biker churches and, once, a man wanting to start a paintball church.

At Life Brand, services are held Tuesday nights, because "weekends are the only time we have to be with our horses," Gregory says.

Services are short, sermons coated in Western allegories, and no one passes a collection plate (or boot, or hat), lest the suspect materialism of megachurches and televangelists encroach on simple faith.

"The cowboy is a way more simple human being," Gregory says. "Take an old cowboy and he can get on a horse and just ride and life is complete for him."

Dusty Whidden is drawn to such welcoming simplicity. A bull rider since age 8, he's spent the past two years as a professional bareback bronco rider, supplementing his winnings with construction work until the recession threw him out of a job and landed him with his parents in Ohio. In the rodeo world, he says, vague professions of faith are often used to excuse unhealthy behavior. "People think that if you believe in Christ, you can do anything," he says, noting the professional rodeo circuit sees a fair amount of drug use. "People are needing church more [since] things in society are taking a dive."

While the popularity of cowboy churches might be relatively new, their central message is classically American, says Kathleen Flake, a professor of American religious history at Vanderbilt University Divinity School in Nashville, Tenn.

"Churches from the very beginning were looking to restore the early church of Christ – it was just a matter of how literal they were about it," Professor Flake says. "It is so characteristic of American religion to say we're going back to purer beginnings." Pursuing the unchurched where they are, she says, is testament to the adaptability of American evangelism.

Of course, not everyone at Life Brand is a cowboy. There are even some Silicon Valley transplants. Kenneth Kerwin is a technology entrepreneur who moved to Ohio to study, he says, "nonlinear electro-optical crystals." But he liked Gregory's back-to-basics preaching.

"This church is a start-up," he says. "I sat in other churches, and I sat and I sat. Now I'm doing."