While Heard's site claims to be "for Christians by Christians," it never identifies who is running it, a point which Frykholm said made her instantly suspicious.
"I was shocked that there was no place on the site where you could find out more about the Rapture. … You don't know who these people are," Frykholm said. "My first thought: 'This is someone who wants $40.'"
According to Frykholm, people who believe in the rapture, also known as dispensationlists, are almost always evangelizing, something that doesn't happen on the site.
"That makes me very, very suspicious. I just expected something more, some attempt to reach me as the unsaved," she said. "You justify taking people's money by spreading the kingdom of God. There's nothing there to justify taking your money. … I'd be stunned if people are signing up for this."
Tim LaHaye, one of the authors of the "Left Behind" series, was less skeptical. He and co-writer Jerry B. Jenkins have been pitched several ideas over the years about communicating with those left behind after the rapture, from videos to bumper stickers, but have so far not endorsed any of them.
LaHaye called the Web site "likely very sincere."
"It is not a bad idea to leave behind some type of message for your loved ones or neighbors, giving them the plan of salvation and an explanation for your immediate disappearance," LaHaye said in an e-mailed statement. He added that Christians should talk to family and friends about their beliefs now.
In explaining his hopes for the site, Heard stressed his own strongly-held beliefs, reciting Bible verses in one breath and discussing server security in the next.
Though he won't reveal number of people who have signed up for the service, Heard says that there's been a fair amount of interest from other Christians — particularly those preparing for what they believe is inevitable.
"Nobody knows the day or the hour of the rapture," he said. "It's really an any-minute situation."