At Irene Trammell's Christian fitness club in California, you can work your thighs while you proselytize.
"They would be able to have the Lord's help to lose weight and get in shape because he does want that for us," said Trammel, owner of This Is It! Christian Fitness.
Mark Gadow's Christian Faith Driving School in Maryland gives new meaning to the old bumper sticker "Jesus is My Co-Pilot."
"I'm teaching them a lot about driving and a little about Christianity," Gadow said.
Go online, and you'll find scores of Christian lending companies.
Search through the Good Shepherd Yellow Pages and you'll find Christian plumbers, real estate agents, even Christian used car salesmen.
Faith-based businesses are not new, but Christian business owners say they've become increasingly vocal about their faith in recent years.
It's part of a growing evangelical assertiveness -- from entertainment to politics.
Buyer Should Still Beware
But while Christian businesses say they give to charity and treat their customers according to Biblical principles, there are some hucksters out there.
"There is no doubt that the majority of our business owners are honest, but at the same time we ask our customers to do their due diligence," said Bill Cooper, founder of christiannet.com, an online Christian business directory.
There are those who believe Christian businesses exploit religion to get customers.
"I'm not sure Jesus Christ would have done that," said Boston College professor Alan Wolfe, who studies religion in public life.
He says Christian businesses both hurt democracy -- because they segregate people -- and are bad for Christianity.
"Because their Christianity requires that they go out and save the souls of other people -- people not like themselves," Wolfe said.
Trammell says 26 people have been born again at her gym.
"We welcome people who are not Christian coming in," she said. "In fact, I love it. It gives us an opportunity to show them we are normal people."
She says starting a business is a way for Christians to go beyond the church walls to promote faith -- and fitness.
ABC News' Dan Harris filed this report for "World News Tonight."