And since the Supreme Court’s decision in the Torcaso case, states have clearly been prohibited from making belief in God a requirement for public office, said Ira C. Lupu, an emeritus professor at George Washington University Law School who specializes in church-and-state issues. Mr. Lupu said of the language in the state constitutions: “Of course they shouldn’t be in there. They’re all unconstitutional. They can’t be enforced.”

Image Todd Stiefel, the chairman of the Openly Secular coalition, said, "If it was on the books that Jews couldn't hold public office, or that African-Americans or women couldn't vote, that would be a no-brainer." Credit... David Walter Banks for The New York Times

But there has been no political will to rescind these articles. “Which politician was going to get up and say, ‘We’re really going to clean this up’?” he said.

The state bans have been invoked rarely since 1992, according to legal experts. In South Carolina that year, Herb Silverman, a math professor at the College of Charleston who is an atheist activist, was denied a position as a notary public. His case went to the South Carolina Supreme Court, and in 1997 he won. In North Carolina, after Cecil Bothwell, a writer, won a seat on the Asheville City Council in 2009, his opponents tried to invoke the State Constitution’s atheist ban to deny him his seat, but they soon backed down.

Organizers with Openly Secular see the bans as evidence of the quiet bigotry and discrimination faced by many atheists, agnostics, humanists and freethinkers. They point to a poll conducted by the Pew Research Center this year showing that nearly half of Americans would disapprove if a family member married an atheist.

Pew also found that 53 percent of Americans polled in April said they would be less likely to vote for a presidential candidate they knew was an atheist. Being an atheist was found to be the least desirable trait a candidate could have — worse than having cheated on a spouse or used marijuana.

The Openly Secular coalition, which includes 30 groups and was formed this year, is trying to win greater acceptance for nonbelievers by encouraging them to go public. Taking a page from the gay rights campaign called It Gets Better, the coalition has posted short video testimonies from people who declare that they are happily nonbelievers. Among those who have recorded videos are former Representative Barney Frank and Chris Kluwe, a former punter for the Minnesota Vikings.