By Dan Merica, CNN

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Boston (CNN)-– It’s Sunday in Cambridge, Massachusetts, and a rapt congregation listens to a chaplain preach about the importance of building a community.

A few dozen people sit quietly for the hourlong service. Music is played, announcements are made and scholars wax poetic about the importance of compassion and community.

Outsiders could be forgiven for believing this service, with its homilies, its passing of the plate, its uplifting songs, belongs in a church.

If so, it’s a church without one big player: God.

Sunday’s congregation in Cambridge is a meeting of the Humanist Community at Harvard University and the brainchild of Greg Epstein, the school’s Humanist chaplain.

A longtime advocate for community building, Epstein and his group of atheists have begun to build their Cambridge community and solemnize its Sunday meetings to resemble a traditional religious service.

To Epstein, religion is not all bad, and there is no reason to reject its helpful aspects.

“My point to my fellow atheists is, why do we need to paint things with such a broad brush? We can learn from the positive while learning how to get rid of the negative," he said.

Godless congregations

For Epstein, who started community-building at Harvard nearly 10 years ago, the idea of a godless congregation is not an oxymoron.

“We decided recently that we want to use the word congregation more and more often because that is a word that strongly evokes a certain kind of community - a really close knit, strong community that can make strong change happen in the world,” he said.

“It doesn’t require and it doesn't even imply a specific set of beliefs about anything.”

Epstein is not alone in his endeavor. Jerry DeWitt, who became an atheist and left his job as an evangelical minister, is using his pastoral experience to building an atheist church in Baton Rouge, Louisiana.

This Sunday, DeWitt's congregation will hold its first meeting as a "Community Mission Chapel."

"When you become a part of this congregation, this community, you are going to become part of a family," DeWitt told CNN. "There is an infrastructure there for you to land in. There is going to be someone there to do weddings and to do, unfortunately, the funerals."

READ MORE: Unbelieving preachers get help to 'come out' as open atheists

Sunday school for atheists

As members of the Cambridge congregation file into a wood-paneled classroom at Harvard, singer Shelley Segal greets them with a few songs from her latest recording, called simply, “An Atheist Album.”

Taking a hint from the theme of the event, Segal strums on her guitar and belts her song, “Gratitude.”

“I don't believe in a great power to say thank you to,” Segal sings. “But that won’t take away from my gratitude.”

After the music, Epstein offers a few words of greeting before the meeting gets to its heart: a discussion about compassion.

A four academics and a journalist discuss the effects of religion on raising children and their ideas about compassion. Congregants listen intently, some even taking notes.

Each service has a message – compassion, evolution or acceptance - after which congregants engage in a lengthy discussion.

Before the main event, kids are invited to what some parents refer to as “Sunday school,” where Tony Debono, a biologist Massachusetts Institute of Technology, teaches the youngsters about evolution, DNA and cells.

There's little talk about organized religion, positive or negative.

Likewise, down in Louisiana, said his atheist services will not be anti-religion.

"What we are looking at doing is different," DeWitt said. "If you are a religionist and you come and sit in our pew, the only way you can leave offended is because of what you don’t hear and what you don’t see. We won’t be there to make a stance against religion or against God."

Coming out of the closet

In the last few years, the number of “nones” – those who don’t associate with any organized religion – has grown at a rate faster than any other group. Nones now represent one in five Americans, according to a 2012 Pew Research Center poll.

Although the number of atheists has grown, too, there are still a large number of “nones” that choose not to associate with the label “atheist.”

Some at Harvard’s Humanist congregation fall into this category.

“I don’t particularly have a religion,” said Anil Nyer, a neurologist who brought his daughter to Humanist Sunday school. But Nyer also said he didn’t want to label himself as an atheist.

One reason to shy away from the atheist label: Many Americans hold a negative impression of nonbelievers.

According to a recent Public Religion Research Institute poll, nearly 40 percent of Americans believe that atheists are changing American culture for the worse.

“Whenever we put atheists on a list like this and we compare them to other groups, atheists tend to come in towards the bottom of that list,” said Robert P. Jones is the CEO of Public Religion Research Institute.

“Americans tend to hold a lot of reservations about atheists.”

Epstein hopes his congregation can change that.

By formalizing meetings and building a strong community, the Harvard group hopes it can be a model for other atheist congregations forming around the country.

More atheists may come of the closet if they know a congregation will be there to support them, Epstein said,

“Being an atheist is something we want people to come out and be,” said the Humanist chaplain. “There are so many people, probably millions, who are humanists or atheists or nonreligious in private and nobody knows."

Epstein said he gets e-mails daily from people founding atheist meet-up groups.

“Tulsa, Oklahoma; North Carolina; London; Vancouver, Canada; Houston, Texas,” Epstein said, listing the sources of the most recent e-mails.

“One part of what we are saying is come on out and let your neighbors know” about your disbelief, he said. “It is not going to make you worse of a person, it is going to make you a better person to be more open about who you are.”

Rituals for the irreligious

For the last few years, the Humanist Community at Harvard has operated out of a small three-floor walk-up off the bustling streets of Harvard Square. The walls are littered with posters about atheism – tributes to famed atheists Eddie Izzard, Seth MacFarlane and Stephen Fry.

Because of the scattered furniture and the Harvard dorm feel, Epstein jokingly describes the space as “college broke chic.” That’s being generous – but it's also about to change.

Starting in the fall, the Humanist Community at Harvard will begin meeting in a nearly 3,000-square-foot community center with an event space for nearly 100 people.

Although the plan is to use the space at the group’s headquarters, it will also serve as a broader community center for the group that Epstein and others are trying to build in the Boston area.

“What we really would like to see is a community center where people can come by at anytime and to use it as a space to study or have a meeting for various committee,” said Chris Stedman, the assistant humanist chaplain at Harvard.

Stedman said he sees the new building as a place for people to gather, not only to become part of a humanist community, but to also become more engaged with the world.

When he talks about his plans for the future, Epstein appears to long for a time when the new community center could mimic aspects of church - a place for baby-naming ceremonies, weddings and funerals.

The success of an atheist church will depend on walking the thin line between too much and too little ritual, Epstein said.

Humanists boast a proud freethinking streak, and some at the Harvard event said they don’t want to be associated with any sort of dogma or belief system - or even a system based on disbelief.

Anyway, Esptein said his congregation will be less a group of people united by beliefs - or disbelief - and more like an opera, or a painting.

“Our community is like a work of art," he said. "Hopefully people will respond to that work of art and it will garner controversy and discussion like a work of art."