The free app--available at http://a.tapstack.com/jeary/pfp--presents instruction and insight to help Christians better communicate their faith. With more than 1,600 downloads since July 1, the app is equipping believers with techniques for sharing their testimony and leading Sunday school classes, small groups and worship services, Standard officials said.

Sarah Felkey, Standard's marketing manager who developed the application, originally saw it as a promotional piece, but soon discovered that it was a product all its own. "We are reaching an entirely new audience who might not have known about Purpose-Filled Presentations otherwise," she said. "By offering this app, we generate sales for the book, but we're also getting valuable content out to more people through this channel."

For retailers, the app also functions as a preview of the book, giving a more in-depth cross-section of the content than the first chapter featured on the book's Web site.

Standard Publishing President Larry Carpenter said the company will pursue other iPhone applications. "This first application was intended to gauge the response to this new content delivery method," he said. "With this level of demand, we are pursuing more mobile applications."