A Presbyterian glancing around the church would find lots of company — if they're over age 50. With 70 percent of their churchgoers over that age, Presbyterians are the "oldest" religious group in the nation.

United Methodists, Anglicans and United Church of Christ come next, with more than 60 percent of members eligible to join AARP.

If you're looking for youth, check out mosques, where nearly half the worshipers are under 30. So are 1 in 3 Buddhists and Hindus.

As religious groups across the nation grapple with ways to grow and sustain membership, new research underscores the pressure on mainline Protestants. They've watched the 50-plus crowd become an ever-growing share of membership, according to a survey by the Pew Research Center, while emerging faiths in the United States and groups with no religious affiliation enjoy the largest share of young faces.

How to keep a church vibrant in this cultural landscape is a constant question facing religious leaders across the nation.

"A church's age is important because it reflects its ability to pass its life to new generations," said Dwight Zscheile, an assistant professor of congregation mission at Luther Seminary in St. Paul. "A faith community without that ability doesn't have much of a future."

The age statistics were gleaned from a survey of more than 35,000 Americans involved in Pew's 2015 report on America's changing religious landscape. Last month the Pew center highlighted the "oldest" and "youngest" groups in a separate report. The figures, including median ages, are just for adults.

The oldest were Protestants who emerged in Europe several hundred years ago, noted Zscheile. That includes the Evangelical Lutheran Church in America, which has deep roots in Minnesota but just 1 in 10 adherents under age 30, according to the survey.

The youngest groups included newer faiths in the United States, as well as those categorized as no faith and agnostic. More than 80 percent of Muslim adults are under age 50, the survey showed, including 4 in 10 under age 30.

In the middle are denominations such as Roman Catholic, which is split roughly in half between younger members and those over 50. Same is true for Jews, American Baptists and Unitarian Universalists.

Wake-up call

Topping the survey's "oldest" list are two Presbyterian denominations, including the 1.7 million-strong Presbyterian Church (U.S.A.). Just 8 percent of the worshipers are under 30.

The Rev. Jeff Japinga, who oversees the Presbytery of the Twin Cities Area, was already keenly aware of the trend. But to be at the top of the age list was "a wake-up call," he said.

"We are a church that wants to be inclusive of all people, that's how we see ourselves," said Japinga. "But when data comes back that's so different, it's a red flag."

It's not easy to attract new people to an old faith, he admitted.

"People already have an image of what we are," Japinga said. "Changing that can't happen overnight."

Many churches are trying to make themselves more relevant, working on community needs such as affordable housing and food security, and offering more volunteer and educational opportunities.

That's something many United Church of Christ churches have been doing for decades, but they still ranked second oldest in the survey. The Rev. Shari Prestemon, who heads the Minnesota Conference United Church of Christ, said it shows there's no "magic bullet" to growing a church.

"This reflects a much larger societal shift, which is the shift to 'Nones' [no religion]," said Prestemon. "It's difficult because it's a cultural phenomenon, not just what a church is doing or not doing."

New strategies

House of Hope Presbyterian Church, founded in 1849, stands between two worlds. Its home is a stately limestone church on historic Summit Avenue in St. Paul, but its front yard has been dug up for a community garden whose fresh vegetables are donated to food shelves.

It offers the traditional carillon recitals, choir school, a knitters group — as well as a Sunday speakers series, volunteer opportunities at a domestic violence shelter, significant support for a homeless youth project and more.

The Rev. Julia Carlson said the graying in the pews has forced a new way of thinking.

"In the past, emphasis may have been on membership rolls," said Carlson. "That has changed. What we're trying to do is focus on the community, whether they want membership or friendship."

Larger churches may be in a better position to replace older worshipers, said the Rev. John Crosby of the 5,000 member Christ Presbyterian Church of Edina. The church has 1,000 junior and senior high students, he said. And it offers five worship services in three styles, traditional, contemporary, and "next generation."

But even big churches have to be thinking of ways to attract and keep members, he said.

"If you're not being pushed into places outside your comfort level, you may not be doing enough," said Crosby, who left the main Presbyterian Church in 2012 to create a separate Presbyterian denomination.

The youngest religious groups, such as Muslims and Hindus, are primarily a product of immigration to the U.S. from Asia, the Middle East and Africa, and higher rates of childbearing.

Older and older

Compared with a similar 2007 Pew study, nearly all mainstream Christian denominations got "older." That means fewer folks of childbearing age will be replenishing the church rolls, filling Sunday schools and choir lofts, and bringing life to a church.

But the aging trend is not all bad news, religious leaders insist. Older members often have more time to volunteer, are generous donors, and offer loyalty and continuity in a changing world. The hard knocks of life have given many a level of compassion not seen among the untested.

They also note that aging alone is not shrinking churches.

"There are a lot of other factors — fertility rates, immigration, religious switching — that all come into play," said Elizabeth Sciupac, a Pew research associate. "There is so much going on as to why and how these groups are changing. It's impossible to predict what will happen in the future."

Jean Hopfensperger • 612-673-4511