The billboard sits near the busy Beach Boulevard and 19th Street in Westminster. The message is posted in huge letters, "Don't believe in God? You are not alone."
"Our main purpose is to gather non-theists under one umbrella," said Bruce Gleason from the Orange County Coalition of Reason. "And have them share with others the idea that human beings can be good without God."
"I was really shocked to see it," said Pastor John Furman from First Presbyterian Church of Westminster.
Furman said everyone is entitled to an opinion but admits he was surprised when he saw the billboard, which sits less than half a mile from his church.
"I think of a scripture in the bible that says 'a fool says in his heart there is no God,'" said Furman. "So really I thought it was a foolish thing to do."
"This sign is not meant to be attacking religion," said Gleason. "The word 'God' here is a generic place-holder for the supreme being."
"I was confused," said San Clemente resident Bonnie Whitney. "And I actually don't know who the company is that put it up. Never heard of that organization."
The O.C. Coalition of Reason is made up of 14 different local groups including atheists, agnostics, and humanists. The coalition director said they are among the 15 percent of Americans that are not affiliated with any religion.
"Athiests are just as moral as everybody else," said Gleason. "We have jobs, we go to school, we have families."
Coalition officials said the sign is a gift from an anonymous philanthropist in Philadelphia. Officials said the billboard cost nearly $6,500. So-called "godless billboards" have recently gone up in several cities in California, including Los Angeles, Fresno and Sacramento.
But not everyone cares to see the signs. At least two billboards were recently vandalized in Sacramento. In Westminster, many agree the billboard catches the eye and some hope it will get people sharing ideas. The billboard is expected to stay up for 30 days.