As they gathered over a banquet of roast chicken and rissole potatoes on May 30, 1948, members of Our Lady Help of Christians Catholic Church had every reason to think the future of their Larimer parish would be as golden as the 50th anniversary they were celebrating that night.

In its first half century, the parish had been a spiritual and cultural hub for the Italian immigrant community, officially witnessing some 2,918 marriages and 13,125 baptisms

And the landmark sanctuary — with its deep, round-arched windows and its trio of golden-colored domes — stood as a point of pride for the neighborhood.

“May Divine Providence grant to the parish of Our Lady Help of Christians continuance of grace, that its future may be no less fruitful and its history no less glorious in the annals of eternity,” the anniversary program said.

But the parish would close its doors just over 40 years later, with many of its congregants having long since moved to eastern suburbs and blended into the American melting pot.

The sanctuary had a second life as home to an independent church before it, too, closed in 2008 and put the building on the market. Since then the church has stood silent, its windows and doors boarded up like those of some other houses on its block. Ragged vines cling to the church walls, graffiti mars the Corinthian pillars, and there’s more tarnish than gleam to the domes. Inside, the bare, cavernous sanctuary has been strewn with litter and marred by blasphemous graffiti.

The Rev. Armenia Johnson, chief apostle and general overseer for Heavenly Vision Ministries -- the last occupant of the building -- shows the damage to the sanctuary. Danese Kenon/Post-Gazette

While the sanctuary’s story is unique, the arc of its rise and fall is familiar.

Throughout the older neighborhoods of Pittsburgh and surrounding communities, and in cities throughout the North and Midwest, many historic sanctuaries have fallen silent, their congregations dispersed.

Within the Pittsburgh city limits alone, the Post-Gazette has found nearly two dozen former churches and synagogues that currently sit unused. Some are well-maintained, others are deteriorating to almost dangerous levels.

That tally doesn’t count the additional shuttered sanctuaries throughout other Allegheny County municipalities, or ones like the former Holy Trinity Catholic Church in Duquesne, recently demolished after storm damage dealt a mortal blow to the decaying structure.

Nor does it count the many others in and around Pittsburgh that have been renovated and now serve as restaurants, banquet halls or other uses. Some become landmarks in their new life. They include Church Brew Works in Lower Lawrenceville — a restaurant reminiscent of a German-style beer hall, set amid stained glass and large brewing kettles — and the Grand Hall at the Priory in East Allegheny, which has hosted everything from wedding receptions to boxing matches. Both are in former Catholic churches.

And some vacant sanctuaries remain in limbo, such as the historic former Albright United Methodist Church in Bloomfield, now at the center of a dispute between preservationists and its Methodist owners, who say the cost of restoration is prohibitive and want to sell it to a developer who plans to raze and replace it with a retail development.

Number of empty churches to grow

The supply of surplus houses of worship will soon greatly expand.

The Roman Catholic Diocese of Pittsburgh is considering the closure of dozens of its church buildings across six counties, the biggest restructuring since it shuttered Our Lady amid an earlier wave of closings in the early 1990s.

The diocese says that when it deconsecrates a church, it typically removes sacred objects and maintains the structure until it’s sold, although sometimes buildings later deteriorate under new ownership.

The diocese is contending with a steep decline in priests and church participation, as well as demographic pressures — people moving to newer suburbs, families having fewer children, young adults drifting away from religion with uncertain prospects of ever returning.

The former St. Matthew is one of several former Roman Catholic churches that are no longer being used. Steve Mellon/Post-Gazette

Similar factors are pressing on other historic religious bodies that often built sanctuaries in neighborhoods where their people no longer reside in large numbers. Episcopal, Methodist, Presbyterian, Lutheran, Eastern Orthodox, Byzantine Catholic and various Jewish denominations have closed multiple sanctuaries in urban neighborhoods and smaller cities and towns.

Especially affected are old immigrant neighborhoods that once re-created the sacred map of Europe in a tight jumble of steeples. But it’s also true of small downtowns whose historic supply of “First” churches often exceeds the demand.

Two former Presbyterian sanctuaries in Carnegie now host a banquet hall and a mosque. Baptist, Methodist and Presbyterian churches in the same Dormont neighborhood closed within a few months of each other in 2013 and 2014; one is now for sale, another is becoming a Buddhist temple and the third is now a campus for a non-denominational church.

The sacred landscape is undergoing a re-mapping that earlier worshipers could barely have imagined when they built their brick, stone or wooden sanctuaries to endure practically as long as the eternity proclaimed within their walls.

“In their mind, they were building for generations,” said the Rev. Charles Bober. He’s a former pastor of St. John Vianney Catholic Church in Allentown, which closed earlier this year due to declining numbers. “They just never would have thought their community would change.”

Gem of the architectural fabric

But they do — sometimes tumultuously when steel mills close, sometimes gradually when people filter out to suburbs or just drift away from the old-time religion.

And some see that as a loss not just to congregations but to their wider communities.

Often, a house of worship is “the greatest form of architecture on a given street,” said Jack Schmitt, the former longtime chair of the religious architecture heritage committee of Preservation Pittsburgh. A decaying landmark church can drag down a neighborhood, and a healthy one can lift it up, he said.

“When you come outside your door in a city area, you almost always see a church, and it adds to the architectural fabric to which our children are exposed. It makes their imagination soar,” said Mr. Schmitt, who helped spearhead the restoration of the landmark Calvary United Methodist Church in Allegheny West and has consulted with others seeking to restore historic sanctuaries.

A house of worship “makes the people feel secure in the neighborhood because it reminds them of the presence of God, even if they’re not parishioners, even if they’re not religious,” Mr. Schmitt said.

Robert Jaeger, president of the Philadelphia-based Partners for Sacred Places, said houses of worship have a “halo effect” on their neighborhoods via direct spending by congregants, boosting social cohesion or making the street more attractive for other investors.

“There’s an economic value to these places, there’s a cultural value, there’s a streetscape value, there’s a social-service value,” said Mr. Jaeger. “Do we really want to see all these places gone?”

But keeping them in place is costly. Beautiful buildings age and decay over generations, dwindling congregations strain to replace ancient, inefficient heating systems, old buildings often aren’t suited to modern standards of wheelchair access and other uses. Air-conditioning is often out of reach.

Mr. Jaeger’s organization tries to help struggling congregations stay in operation through such means as sharing their space — and expenses — with civic organizations involved in arts, education or social services such as child care.

But the headwinds are strong, he acknowledged, and not just in cities.

“Even the older suburbs were once considered immune but are starting to face the same issues,” Mr. Jaeger said.

When neighborhoods change

The issue of church closings often is closely tied with those of race and class. Many closed sanctuaries, such as Our Lady, declined when white parishioners moved out of a neighborhood and people of color, often poorer, moved in. Sometimes a locally based congregation will purchase the building, but it may lack the resources to maintain it. And churches are often not the only shuttered buildings.

“There is so much vacancy as far as other houses, other large commercial buildings. There are two vacant schools in the neighborhood,” said Demi Kolke, community development manager of Operation Better Block, an organization focused on Homewood revitalization.

But many other churches do thrive in Homewood, she said, drawing not just locals but outsiders. If more came, they might become more invested in the neighborhood’s health. “Where people worship, where they pray is oftentimes where they will be comfortable exploring more,” she said.

She hopes that denominations consider the community impact of a church closing.

“I can understand the business side of it,” such as the availability of funding and clergy. But keeping a sanctuary open “does have tremendous value” to its neighbors.

She cited the case of the Bible Center Church, which is restoring a vacant sanctuary across from Faison Arts Academy in South Homewood. The church plans to use the historic structure for everything from student programs to training of teachers and parents, with an emphasis in such areas as science, technology and math.

To be sure, new sanctuaries are being built in growing suburbs, and many of them thrive.

Father Bober has seen that first-hand now as pastor of fast-growing St. Kilian Parish in Cranberry, which in September dedicated a new church (and partly adorned it with artifacts from shuttered churches, including St. John Vianney.) Evangelical Protestant congregations known as megachurches have built large sanctuaries, typically in auditorium-like settings with large video screens and little of the ornamentation associated with old churches.

Shifts in worshipers

The former Ebenezer Baptist Church in the Hill District is barely recognizable as a church now. Danese Kenon/Post-Gazette

Overall, though, growth is the exception.

Indeed, while suburban migration and other demographics explain some of the decline in older houses of worship, an undeniable factor is the decline of worship itself.

Nearly a quarter of American adults, and a third of young ones, answer “nothing in particular” when asked their religious affiliation, according to a 2015 Pew Research Center report. In 1990, fewer than 1 in 10 said so.

Catholics and mainline Protestants are declining as a share of the population, the Pew report said, while evangelical Protestants are holding their own.

Catholic sacramental observance is down significantly, the Diocese of Pittsburgh says.

And religious groups overall in greater Pittsburgh had a net loss of at least 15 percent of their adherents between 2000 and 2010, led by declines among Catholics and historic Protestant denominations, the Association of Statisticians of American Religious Bodies reports. Those losses outpaced smaller gains by some evangelical Protestant, Mormon and other groups.

While some congregations thrive even in economically depressed areas, many historic congregations lose the sense of energetic mission that built them generations earlier.

“We’ve seen this across denominational lines,” said the Rev. Jeffrey Johnson, regional pastor for the American Baptist Churches of Pennsylvania and Delaware. “They go from community-based congregations to commuter-based congregations, where you have people coming back into the church because they have some heritage there. But they have lost just about every bit of connection with the community. If the congregants don’t adopt the community as their own, the clock is ticking.”

Rev. Johnson said dwindling churches typically carry on until a crisis knocks them out — a burst water pipe or a killer heating bill. The Great Recession “really became for many churches a death knell,” he added.

When churches do close, they often use their remaining assets to support the launch of a congregation elsewhere, or a student ministry. “In closure there’s new life,” Rev. Johnson said.

When he helped one church close up shop, members said they felt they had failed. “Not if you close well,” he told them.

Not one church mentioned in the Bible is open today, he said: “So churches have life cycles. We have to accept that.”

And sometimes the cycle renews itself. The former St. Elizabeth Church, built by a Slovak Catholic parish in the Strip District, spent recent years as a nightclub, the Altar Bar. Now a sale is pending to Orchard Hill Church, a large Franklin Park-based church, as a permanent home for its recently launched urban campus.