The billboards, part of a campaign sponsored by the Sacramento, Calif.,-area chapter of the Freedom From Religion Foundation, is calling on the growing number of people who say religion isn't part of their lives to "come out of the closet."
"It's because atheists are starting to speak up and they're beginning to identify each other and find out they're not alone," said Judy Saint, the president of the group's local chapter. "There are a lot of non-believers and this time of year, they feel like they're all alone."
The 55 billboards include quotes like "Live for now, not for after," and "A life of love, no Gods required," all feature real people from Sacramento, including their photo and their name.
But if Sacramento's faith community doesn't agree with the message, they aren't offended by it.
"Sacramento is a very religious community, lots of good is being done by religious people," said Interfaith Council of Greater Sacramento spokesman Jon Fish. "I don't have any grief with any of that."
Freedom From Religion is a several-year-old campaign working to get religion out of government. The billboards will be up in the Sacramento area for at least a month.