"Don't believe in God? You are not alone."

That statement is expected to plaster a major Phoenix highway billboard by the week's end.

The Arizona Coalition of Reason and the American Humanist Association (AHA) are sponsoring the billboard. The campaign targeting "nontheists" is timed to coincide with the AHA's 68th annual conference in Tempe this week. The term nontheist is generally considered an umbrella label for atheists, agnostics and other people who do not believe in God.

The conference is billed as one of the largest national gatherings of nontheists and attracts between 300-500 attendees.

Organizers for the gathering did not know if the conference had ever been held in Arizona but said records show it has been held in other states for at least the past 20 years.

Karen Frantz, a spokeswoman for the AHA, said the billboard is aimed at supporting people who might be afraid to admit they don't believe in God.

"I'm sure there are plenty of people who are wary of coming out as an atheist or a humanist," Frantz said. "There are some communities that tend to be much more religious and people may worry about backlash.

I would say there's also fear of coming out as a nontheist to people close to them because they're afraid their parents or friends wouldn't approve."

The billboard will refer people to the Arizona Coalition of Reason's Web site, www.arizonacor.org.

United Coalition of Reason chapters and the national organization have led other public campaigns involving prominent advertising of their beliefs.

In Washington, D.C,. during last year's Thanksgiving season the organization was involved in posting bus ads asking readers: "Why believe in God?"

The billboards caused a stir but once the dust settled, Frantz said the campaign served its mission.

"The majority of the responses were favorable," she said. "We actually had a woman immediately sign up. She had never heard of us before and was happy to find people (who share her beliefs)."

Frantz said the Valley billboard is expected to be up by Friday but said she could not release information on its exact location because those details are still being worked out with the advertising company.

The conference will honor Paul Myers, a biologist at the University of Minnesota's Morris campus who is known as an outspoken supporter of Charles Darwin's theory of evolution, as the 2009 Humanist of the Year.

Myers blog "Pharyngula," which covers science, politics and culture, has been heralded by Nature Magazine and won several science blog awards.

The conference also includes local speakers.

Dr. Donald Johanson, a paleoanthropologist and director of the Institute of Human Origins at Arizona State University, will speak at the conference. Johanson is well known for his 1974 discovery of the fossil, "Lucy," the 3.2 million-year-old remains of the Ethopian hominid known as Lucy.

Assistant House Minority Leader Kyrsten Sinema, a Phoenix Democrat, will is also scheduled to speak.

For a full list of speakers and to register: www.americanhumanist.org.