Each year, on the first Thursday of May, elected officials gather in Washington, D.C., and around the country for the National Day of Prayer. It's a day when public servants from the president on down encourage Americans of all faiths to pray and contemplate the role of the divine in their lives. But 20 percent of Americans identify as religiously unaffiliated or simply don't believe in God -- and many of them aren't comfortable with the idea of a government-sanc tioned occasion that shuts them out entirely.

This week, Rep. Mike Honda (D-Calif.) and Delegate Eleanor Holmes Norton, a Democrat who represents the District of Columbia in the U.S. House of Representatives, introduced a resolution to create a secular alternative to the National Day of Prayer. The one-time occasion, known as the National Day of Reason, would be observed on Thursday, May 5, the same day as this year's National Day of Prayer. According to the resolution's authors, the National Day of Reason would provide an opportunity for the religious and non-religious alike to come together and recognize "the importance of reason in the betterment of humanity."

"The application of reason has proven to improve the conditions in which people live, offer hope for human survival on Earth, and cultivated intelligent, moral, and ethical behaviors and interactions among people," said Honda in a Tuesday press release. "I encourage everyone to take this occasion to reflect upon the way that philosophical principles developed during the Age of Reason influenced our Founding Fathers as they formed our country and how the employment of reason, critical thought, the scientific method, and free inquiry can help resolve human problems and improve the welfare of humankind.”

Honda introduced a similar resolution last year, only to see it die in committee. Atheism and outspoken support for non-traditional religious beliefs remain, for the most part, a third rail in politics. There isn't a single openly atheistic member of Congress, and only one -- Rep. Kyrsten Sinema, a Democrat from Arizona -- who lists herself as unaffiliated. More than 90 percent of members of Congress identify as Christians, and an entire 57 percent, including Honda, consider themselves Protestants.

But the American Humanist Association, a nonprofit that lobbies Congress on the separation of church and state, hopes to see more progress on the resolution this year, perhaps starting with a companion measure in the Senate.

"Our final hope would be to have something similar to what's done with the National Day of Prayer, where you have a presidential proclamation being issued calling on people to use their reason, to come together, to unite and essentially celebrate the same values that are in the National Day of Prayer but without the call to prayer," said Matthew Bulger, a legislative assistant at the American Humanist Association.

"The National Day of Prayer has a lot of good things about it," he went on. "They celebrate the values of freedom, civil rights -- all things that atheists and nontheists want to be able to join into, but would feel uncomfortable praying about because it contradicts their religious views."

Every year on the National Day of Prayer, the president signs an official statement stressing the importance of expressing one's faith. And while President Barack Obama's proclamations have included gestures of inclusion toward nonbelievers as well as the faithful -- "I invite the citizens of our Nation to give thanks, in accordance with their own faiths and consciences, for our many freedoms and blessings," the 2015 proclamation read -- the day is still most closely associated with Christianity, a religious identity that 75 percent of Americans claim.

For example, the National Day of Prayer Task Force, an organization that coordinates events nationwide and will host congressional lawmakers in a Capitol Hill ceremony next month, says it "represents a Judeo-Christian expression of the national observance, based on our understanding that this country was birthed in prayer and in reverence for the God of the Bible."

This intersection of religion and politics has caused controversy in the past, with groups unsuccessfully challenging the National Day of Prayer as a violation of church-state separation.

Groups like the American Humanist Association acknowledge that the current political climate makes it hard to take much of a stand against the National Day of Prayer. But they're encouraged by recent moves at the state and city level to break up the strictly religious tone of the day's events.

In states like Delaware, Iowa and Nebraska, governors have officially declared the first Thursday in May a National Day of Reason. The governors of Iowa and Nebraska are both Republicans, which some see as a sign that controversy over the effort is waning.

For Bulger, it's important to send a message to all Americans that they are equally welcome to engage in civic life, regardless of their faith -- or lack thereof.

"The National Day of Reason is an observance worthy of government recognition not only because of the values it promotes, whether it's reason-based public policy or community cohesion, but because of the idea that when government decides to take part in a private observance, it needs to do so on the most inclusive grounds possible," he said. "It cannot effectively say to a whole segment of the population that you are not able to participate in American civil life because you do not hold the same religious views that we hold."