An executive at the American Humanist Association recently claimed that 24 members of Congress privately confessed to being atheists.
The group's communication director, Maggie Ardiente, said that although there are no openly atheist members of Congress currently in office, there are dozens of atheist politicians in the legislature, the Huffington Post reports.
"We already know of 24 members of Congress who have told us privately that they don't believe in God, but they won't come out, of course, and if we tried to out them they would deny it," she told attendees at the World Humanist Congress this month.
"We're really behind when it comes to humanism in politics."
The last openly atheist congressperson was Rep. Pete Stark, a California Democrat. Stark lost his seat in 2012.
In the UK, it is far more common for openly atheist politicians to be elected and religious affiliation is less of a concern to the voting public.
"Americans have a much stronger civil religion and a much stronger sense of being a nation under God and chosen by God," Lancaster University Professor of Sociology of Religion Linda Woodhood told the Religion News Service.
"It's a bit treasonable, unpatriotic, to reject religion.
"Whereas in Britain, civic identity isn't as bound up with being religious anymore. You don't seem unpatriotic or amoral if you express your atheism."
Prime Minister David Cameron has expressed a desire for the country to be more religious, however.
"I believe we should be more confident about our status as a Christian country," he wrote in the Church Times, "and, frankly, more evangelical about a faith that compels us to get out there and make a difference to people's lives."