From the sound flowing from Beth Eden Baptist Church in West Oakland when the congregation and gospel choir join in a joyful crescendo, a passerby could be fooled into thinking the pews inside are packed.

But on a recent Sunday morning, that sound was being made by fewer than 50 people in a church that can comfortably seat 400. And less than a decade ago, it did. Longtime congregants recall the days when people spilled into the aisles.

“When I was a kid, you couldn’t even find street parking on Sundays if you didn’t get here before a certain time,” said Aisha Jordan, 39, whose grandparents began attending Oakland’s oldest African American Baptist church in 1941.

Beth Eden isn’t the only predominantly black church in West Oakland where attendance is dwindling, and Jordan’s story helps explain why. The Oakland native has watched lifelong friends disappear from the church at 10th and Adeline streets after leaving for less-pricey locales such as Antioch, Pittsburg, Stockton and Sacramento. Six years ago, she left too, landing in Novato after living in San Francisco for a bit.

The departures are part of a transformation of neighborhoods that were once nearly all-black. In 1980, Oakland’s African American population numbered 159,000, or 47 percent of the city’s total. Thirty years later, it had shrunk to 109,000 — 28 percent.

Some of those who left town try to maintain a connection to their old churches, making it to perhaps one or two services a month. However, that’s not enough to maintain the financial foundation of churches that rely on tithes and offerings for their survival.

“The rug has been pulled out from under our church family,” said the Rev. Ken Chambers, who leads West Side Missionary Baptist Church just off Seventh Street in West Oakland. “It’s devastating.”

The problem is pervasive among Oakland’s black churches, said Michelle Myles Chambers, the West Side pastor’s wife and program assistant for the San Francisco Foundation’s Faiths program, which connects religious organizations with support from nonprofits and foundations.

Pastors say younger people aren’t nearly as interested in organized religion as their parents were, or don’t like the messages being conveyed in services. Older members have died. But the biggest problem, they say, is the flight of African Americans from Oakland.

Churches have reacted in different ways. Some, like Beth Eden and Greater St. Paul Missionary Baptist Church on Martin Luther King Jr. Way in Uptown, have cut back on the number of weekly services they offer. After many of its congregants moved to Stockton, Glad Tidings Community Church formed a satellite church in the Central Valley city.

The Oakland churches are also making it known that their halls are open to people of all races and ethnicities, including those who have just moved to the area. With the city’s Latino population having more than tripled since 1980, West Side is among the churches that have begun sharing their buildings with Spanish-speaking congregations to help pay the mortgage.

“If your congregation is in Oakland, the neighborhood around it is probably changing,” Myles Chambers said. “So it’s advantageous to go out and welcome new neighbors into the facility.”

The Rev. Gillette James has been Beth Eden’s pastor for 46 years. He will retire this year, and the church is looking for a replacement. The incoming leader not only will need to be “emotionally prepared for the downward spiral of regular attendees,” James said, but also should be willing to work with an associate pastor who would lead, “at least half the time, members of a different ethnic group.”

James said he has tweaked his sermons in recent years to be more inclusive of white, Asian American and Latino visitors. For example, he might leave out that funny anecdote from a recent issue of Ebony magazine.

But the majority of Oakland’s new residents aren’t likely to visit a predominantly African American church, pastors say. And while many people in their 20s and 30s consider themselves spiritual, the Rev. Chambers said, most are not churchgoers.

In fact, the relationship between newcomers and Oakland’s black churches has been adversarial at times. In October 2015, Pleasant Grove Baptist Church on Adeline Street received an advisory letter from the city that threatened a $3,500 fine after residents complained about loud choir practice. The city later dropped the threat.

“It’s not how it used to be. People would come to an area and immediately find their home church,” Chambers said. “Well, you got people moving in now, and they aren’t running to the house of the Lord.”

Church has long been the bedrock of African American communities. When black families began moving to California from the South in the 1920s and ’30s, they sought out churches faster than they did doctors. Beth Eden, which was founded in 1889, welcomed many new members in that era.

“They would be on a bus and see a black person dressed up on a Sunday, and they would rightly assume the person was going to church,” James said. “So they would ask, ‘Where do you go?’

“You couldn’t just look that up in a phone directory,” he said.

Among those who keep the Beth Eden afloat amid dwindling attendance are descendants of those members, who were helped by the church emotionally, financially and spiritually during their first lonely days out West.

“Some of these members are well-off, have seen what is happening here and have increased their giving,” James said. “Even if they have moved away, a money order or a check comes each month.”

Chambers said his West Side church hasn’t been as lucky. There are fewer members to tithe, but the mortgage and utility bills remain the same.

“The little savings we had, that little nest egg, has been exhausted,” he said.

Many church families were not forced out of Oakland, and instead chose to move, opting to buy homes or rent in cities with lower crime rates and costs of living. Some, like Greater St. Paul member and choir singer Courtney McGhee, say their quality of life has improved since leaving town. She and her mother moved from Oakland to Antioch when they were looking for a bigger house in 2013.

“I was very excited to move to Antioch. It’s a nicer area, so that’s probably why I wasn’t thinking like, ‘Oh, I'm leaving this place I’ve been all my life,’” said McGhee, 25. But she soon discovered that her time at Greater St. Paul had created ties too important to abandon.

“I don’t want to give up the bond I have with the people at Greater St. Paul,” she said. “I don’t want to start over.”

The drive to church is taxing — she leaves home at 6 a.m. on Sundays to make it in time for the choir’s sound check at 8 a.m. Yet she would still rather make the trip than find another church closer to home.

Then there are churchgoers like the Rev. Mary McCon-Gilmore, a schoolteacher who leads Faith Chapel, which uses West Side’s facilities twice a month. When her landlady in West Oakland died and the family decided to sell the house, she and her husband had to start looking for a new place to live in early 2016.

McCon-Gilmore couldn’t come up with anything affordable in the city. So the Oakland native found a place in Richmond and makes the 11-mile drive every Sunday morning. The commute is worth it, she said.

“I love my church,” McCon-Gilmore said. “My whole life and heart is still in West Oakland.”

Even for worshipers hoping to leave the city, the church remains central to their lives. Gale Mason is one of them. She’s tired of the violence that has killed several of her family members, and she’s been bled dry by the city’s expense. Her family of eight, which includes members of three generations, has been living for the last year in a camper.

As she tries to move elsewhere, the West Side church gives her a sense of security.

“When you go to Bible study, it pulls you through the rest of the week,” Mason said. “It gives you that strength you need.”

For many of those who remain at the shrinking churches, the empty pews are a melancholy reminder of those who once filled them. But the spirit remains alive.

Robbie DeBose, 45, has attended services at Beth Eden for more than 30 years. She moved to Pittsburg a few years back, but her core church family is still in Oakland.

“It’s kind of sad that the church is not full,” said DeBose, wearing her red velvet usher uniform after a Sunday service. “But all we need is one or two people to worship. I come for me.”

On one recent Sunday, the families at Beth Eden, clumped like islands, sang up into the vaulted pine rafters.

“I’m glad to be in the service,” they rejoiced. “I’m glad to be in the service.”

The Rev. James, the pastor, drove the message home.

“My faith, our faith,” he boomed, “is alive.”

Laura Newberry is a Berkeley freelance writer. Email: metrodesk@sfchronicle.com