The original plan called for something far more inflammatory: a billboard saying "All religions are fairytales."
"We want to create controversy and make people think," said Bruce Gleason of Backyard Skeptics, an Orange County atheist club.
But the sign company deemed that ad too incendiary.
So Gleason's group cooked up several tamer slogans (such as "Don't believe in God? You're not alone") and began plastering them on local bus stops and billboards.
The newest sign went up this week along the southbound 55 Freeway, near the Edinger on-ramp.
It depicts "lifelong atheist" Natalie Khazaal saying, "Atheism is philanthropy without mythology, peace without superstition."
Gleason, a Villa Park video producer who films West Coast swing-dance competitions, said the $6,000 billboard will stay up for one month.
"We've been getting a lot of comments from people saying we should have spent that money on charity," Gleason said. "But look at all the Christian billboards. Shouldn't they also be spending that money on charity?"
Two more atheist billboards will appear next month, he said. One, along the 22 Freeway at Valley View, will say: "Faith has no answers. It only impedes questions."
The other, along a street in Orange, will quote Thomas Jefferson.
The ad campaign is financed by "an anonymous donor" to Backyard Skeptics, which boasts 440 members and sponsors assorted activities, including science-related field trips to the Jet Propulsion Laboratory, monthly lectures and occasional movie nights (the latest screening is "The Ledge," about a love triangle involving an atheist and two Christians).
Club members also trek to the Huntington Beach Pier several times a year to proselytize in person--just like their Christian counterparts--with "secular signs" to recruit new nonbelievers.
What do local Christian organizations think of the anti-God billboard effort? Officials with the Roman Catholic Diocese of Orange and declined to comment.