It sometimes feels like church in the auditorium of the Professional Musicians union in Hollywood. It's a Sunday morning, and hundreds of people are gathered to meditate, sing and listen to inspirational poetry and stories.

But then the live band starts up -- performing songs by the Beatles, the Rolling Stones and Jerry Lee Lewis. And instead of a sermon, there's a lecture by experimental psychologist and neuroscientist Jessica Cail about the biology of gender identification and sexual orientation.

This is a Los Angeles meeting of Sunday Assembly, a church for people who don't believe in God. The brainchild of two British comedians, the movement has since spread across the globe, and there are now about 30 chapters from Dublin to Sydney to New York.

There's little God talk at Sunday Assembly, but there is advice by local co-founder Ian Dodd to be authentic. That appealed to divinity student Noel Alumit.

"I don't necessarily have to believe what you believe, but we won't tell you what to believe -- you know, props for that. Respect. Total respect for that," Alumit says.

This was exactly the intent of Sanderson Jones and Pippa Evans when they started Sunday Assembly in the United Kingdom. "There are loads of people out there who want to live better, help often and wonder more," Jones says in a crowdfunding video pitching their idea for godless congregations.

"It's all the best bits of church, but with no religion and awesome pop songs," Evans says. "And it's not a cult," Evans adds.

"But that's exactly what we'd say if it were a cult," the pair deadpan.

This lighthearted approach seems to be reaching a growing number of nonreligious people.

"This is a big boom now of secularity -- people not wanting to associate with religion, not wanting to identify as religious," says Phil Zuckerman, who teaches about secularism at Pitzer College in Southern California.

Zuckerman says his research shows that 20 percent of Americans say they are nonreligious. And among people younger than 30 years old, that number is 30 percent, he says.

"Some people who were raised with religion rejected it for certain reason that leaves them with a bitter taste in their mouth about religion: either they had bad experiences in their church, or they saw hypocrisy in the youth pastor, or they felt that religion was manipulative or all the litany of reasons people might not like religion," Zuckerman says. "Those people are a little bit angry at religion."

He says Sunday Assembly appeals to more optimistic atheists -- those hoping to re-create what they felt was good about religion.

"They miss the community, they miss the music, they miss the multigenerational coming together with people that you might not otherwise be hanging out with," he says.

"But they don't want to go to a place where they have to keep their intellect on hold. They don't want to push pause on the skepticism button in their mind."