A screenshot of Trevor McKendrick's Bible app. Salem Software LLC

Trevor McKendrick may not believe in God, but the Holy Scriptures have proved good business for him. The Salt Lake City software entrepreneur and self-described atheist created two Bible apps for the iPhone that make $100,000 a year, Business Insider reports.

McKendrick’s apps are Spanish translations of the Bible. One is a text version that is free to download and offers in-app purchases. The other is a Spanish audiobook of the Bible that sells for $9.99 on the Apple app store. He credits his success to the audiobook app. It was released a few months after the text-based app and has been more lucrative. In its first year the app made $73,034 in net revenue, followed by $100,134 in its second year.

"That was the moment, where it was, ‘Oh this is not just a side project. This is a living,’" McKendrick told host Alex Blumberg of the podcast StartUp in a Jan. 6 episode.

In his blog McKendrick said the idea for the Bible app came from market research. He wanted to find a niche that could be profitable and was “not swamped by competition.” He found this in the Bible app market.

“It turns out that most of the Spanish Bible apps out there are really bad,” McKendrick wrote in his blog. He said some Bible apps are good but are too generalized and isolate their Spanish-speaking audience.

“My hypothesis was three fold: (1) Whoever was making Spanish Bibles right now was making decent money, (2) I could make a better Spanish Bible app relatively cheaply, and (3) the competition wasn’t too heavy so I’d still be able to be found,” he wrote.

At first the text-only app made $1,475.99 over the course of a month. The app itself took less than $500 to make. A few months later McKendrick hired a professional audio studio to record the entire Bible in Spanish. This recording was used for a separate app where the Bible was presented as a Spanish audiobook.

The second app “made the side project that much bigger. Revenues at that point were around $4k to $5k a month,” he wrote, adding that he hopes to make connections with Spanish-language Christian publishers to expand his business.

“I’m hoping to make friends with people who own copyrights to additional content our customers have asked for. Not only would the in-app purchase revenue be nice, but our customers would love us,” he said.

McKendrick was raised Mormon but later left the church and now does not follow any faith. "I would describe myself as an atheist," he told Blumberg, adding that he has received emails from buyers who say they pray for him or ask him to interpret certain passages for them. “They think I’m a preacher.”

This puts him in a precarious position at times, he said.

"People ask me if I feel guilty or how I justify it. And while I do feel a bit uncomfortable at times, I remind myself that we make a quality product," McKendrick told International Business Times in an email. "Our apps have great reviews and people really like them. It's not like we're selling snake oil or something that's not what it purports to be. We sell a very high-quality Bible app."

When asked if the guilt will stop him from selling the app, McKendrick told Blumberg, "No, I can't. Yes, I have a problem with it. But I can't."

Hemant Mehta, editor of the Friendly Atheist blog, says McKendrick's role isn't necessarily an unethical one.

"Despite what he said, I don’t actually think he’s telling people it’s real. Should he be held responsible for what people take from it?" he wrote. "In any case, I’d probably do the same thing in his situation. He created a great app that someone would have made eventually, so more power to him for cashing in on it."