The 115th Congress was sworn in on Tuesday, and once again, not one of the 535 members of the U.S. House or Senate has stated publicly that he or she doesn’t believe in God.

The religious makeup of the legislative body is overwhelmingly and disproportionately Christian, according to Pew’s “Faith on the Hill” survey. Nearly 91 percent of members of Congress reported their religious affiliation as Christian, while 71 percent of U.S. adults identify as Christian.

Just one member of Congress, Rep. Kyrsten Sinema (D-Ariz.), identifies as religiously “unaffiliated.” She’s been the only “unaffiliated” member of Congress since she was elected in 2012, even as the nation’s ranks of religious “nones” — those who don’t subscribe to a particular religious creed or simply don’t believe in God — have grown to include nearly one-quarter of U.S. adults. Another 10 members of the 115th Congress, all Democrats, declined to state their religious affiliation for the survey.

Pew Research Center

Neither the Christian-dominated nature of the U.S. Congress, nor its lack of atheist representation, are new. The last open atheist, Rep. Pete Stark (D-Calif.), lost his seat to a challenger in 2012. Stark had already been in Congress for over three decades when he publicly acknowledged his lack of religious faith in 2007. No candidate has ever entered Congress as an avowed atheist.

But the religious makeup on Capitol Hill is increasingly at odds with a nation that is becoming more comfortable with non-traditional religious beliefs, as well as the atheist or nontheist community’s continuing fight for mainstream acceptance.

The simplest definition of an atheist is just a person who doesn’t believe in the existence of deities. In the current political climate, however, the word “atheist” has taken on sinister connotations, often used to hint that someone is without a moral center or is openly hostile to the idea of anyone practicing religion.

With lingering controversy over the atheist label, Americans both in and out of public life appear hesitant to embrace it. Nine percent of U.S. adults in a 2015 Pew survey said they don’t believe in God, but a separate Pew study from 2014 found that only around 3 percent of U.S. adults actually identify as “atheist.”

The issue is particularly fraught in U.S. electoral politics. A Pew survey published last year found that atheism was the most significant political liability among a range of possible traits. More than 50 percent of respondents said they’d be less likely to vote for a presidential candidate who didn’t believe in God. This distrust extends beyond politics, with polls regularly showing that many Americans have negative views toward atheists in general.

The lack of open representation in politics is disappointing, said Roy Speckhardt, executive director of the American Humanist Association, a nonprofit that promotes the philosophy that people can be good without a God. But he says it doesn’t necessarily mean the will of nonbelievers is being ignored entirely. Last month, for example, Congress passed an international religious freedom law that included language to protect the rights of people who express “non-theistic beliefs.”

Speckhardt said he’s encouraged by signs like this in Congress, as well as progress on other issues the secular community supports, like LGBT equality, abortion access and civil rights, which aren’t explicitly about religion or lack thereof. But he also believes there are atheists or other nonbelievers on Capitol Hill who are choosing to keep their views private.

“There continues to be this reluctance among elected politicians to be completely open about their non-belief,” said Speckhardt. “They haven’t seen someone get up there, talk about their nontheism and still be able to strongly push an agenda. I think once we get that kind of thing happening, that will help these politicians realize that it’s OK to come out.”

Last year, the secular community had hopes that then-congressional candidate Jamie Raskin, a Maryland Democrat, would help lead this charge. But Raskin, a member of the AHA and a onetime secular progressive folk hero, quickly sought to distance himself from the “atheist” label, telling The Washington Post that he identifies as “emphatically Jewish.” He didn’t clarify whether he believes in God, saying he’d prefer not to answer that question. Raskin won in November and is now among the 30 members of Congress who identify as Jewish, according to Pew’s tally.

An open nonbeliever in Congress would help challenge the stigma that has made atheism an apparent liability in U.S. politics, said Speckhardt. But he believes any lawmaker who is considering saying publicly that he or she doesn’t believe in God could make history without making a big deal about it.

“This doesn’t have to be the defining feature of who they are,” he said. “They can still have the dream of going to Washington and getting things done for good, for everybody, and maybe even get them done better once they point out that they don’t have the shackles of faith tying them down to ideas that aren’t based in reality.”