BRISTOL, England – In front of the altar at St. Paul’s Church, two young acrobats balanced upside down with their toes pointed heavenward. Unicycles leaned against 200-year-old pews and trapezes hung from 40-foot-high scaffolding alongside stained-glass images of Moses, David, and Elijah.

“I love to see the church used like this,” the local Church of England vicar, the Reverend David Self, said, watching 20 teenagers training to become circus performers. “If we worship and celebrate a God who is creative, for me this is part of His work.”

A towering 18th-century landmark in this industrial city 100 miles west of London, St. Paul’s is an emblem of a movement to save the country’s majestic but increasingly empty churches by converting them to inventive new uses. Hundreds of historic houses of worship are being turned into apartments, offices, pubs, spas, shops, and, in the case of St. Paul’s, a brand-new academy to teach circus and theater skills to underprivileged youths.

“These churches are part of the nation’s identity,” a Church of England official, Paul Lewis, who oversees conversions of church buildings, said. “Sometimes the economic reality is that churches have to be closed. At the end of the day, it’s better to have the buildings being used.”

The Church of England, founded by King Henry VIII in 1534, is the country’s largest. But it has closed about 1,700 churches since 1970, as attendance has declined and centuries-old buildings have become too costly to maintain. Fewer than 7% of Britons now attend church regularly, according to a private group that studies church issues, Christian Research. Church of England officials said that while the church has 24 million baptized members in England, only about 1 million of them are in the pews on a typical Sunday.

Many of the buildings being converted are cavernous structures erected in the 18th and 19th centuries, with imposing spires. But especially since World War II, residents have migrated to the suburbs and left behind aging buildings that are extremely expensive to heat and maintain.

Mr. Lewis said the Church of England still operates more than 16,000 churches, and about 500 new ones have been built in the past 35 years, many in new suburban population centers. But, he said, the church continues to shut about 30 buildings a year.

“There is a great sadness surrounding the closure of these historic buildings,” a professor of sociology at the University of Aberdeen, Steve Bruce, said. “But they have to be shut down and sold off. There is absolutely no reason to suppose that there is going to be a great turnaround in church attendance.”

Some of the closed churches have been bought by other religious groups – immigrants sometimes turn them into houses of worship for their faiths. Others have been turned into private businesses. At least three have been turned into rock climbing centers. “This is a living, breathing building that’s still open to the public, and I think that’s what churches are for,” Julian Walker, who runs the Bristol Climbing Center, a converted 15th-century church formerly known as St. Werburgh’s, said.

The interior, with its 35-foot-high vaulted ceilings, has been fitted with artificial climbing surfaces – plywood walls that look like rock faces. Climbers with ropes and harnesses scale the walls, then rappel to the marble floor while people in the coffee shop watch from ancient oak pews.

In other cases, entrepreneurial spirit has moved in right alongside the Holy Spirit, as churches dedicate some of their space to money-making ventures. The Holy Innocents Church in Manchester sold off its adjacent school, which is now the Queen of Hearts, a busy pub catering to college students. The church, however, continues to operate.

The 500-year-old St. Sepulchre-without-Newgate church in London, where the remains of Captain John Smith are buried, is renovating its former vicar’s residence into a luxury apartment. Officials hope to cash in on London’s dizzying real estate prices to help maintain the church.

In a central England town near Birmingham, Walsall, one of the most successful prophets-and-profits redevelopment projects fills a downtown square next to the bus station. An 1892 chocolate-brown Victorian Gothic church, once known as St. Paul’s, has been relaunched as the Crossing at St. Paul’s – a thriving combination of shops and worship space.

Betty Orton, 78, recalled that Church of England officials were close to shutting down the church as early as the 1960s, so she and other parishioners began looking for ways to make it more self-supporting. With donated and borrowed money, they hired an architect and a contractor and divided the church’s huge interior space into three levels.

Today the ground floor is a shopping area. The second level is a busy coffee shop. And the third level, tucked under the vaulted ceilings at the top of the tall stained-glass windows, is a bright chapel where Ms. Orton and about 200 other parishioners attend weekly services.

“An awful lot of effort went into saving this,” Ms. Orton said, noting that the commercial and religious coexist easily: The elevator that carries customers to the coffee shop was specially built to be big enough to carry a casket, for funerals on the third floor.

On the ground level, a small chapel next to the original site of the altar has been perfectly preserved. One recent morning Kenneth Hewitt, 64, knelt there with his head bowed. “I come here to pray to God to keep me free from pain,” he said.

Through a glass door, no more than 30 feet away in the shopping mall, Winsome Lawson was gluing a new set of two-inch-long false fingernails onto a customer in her KhamRo beauty salon. Ms. Lawson, who also does reflexology, Reiki and Indian head massage, said people who were baptized or married in the church often wander in to shop or just to reminisce.

In Bristol, the circus-training center opened in August following a yearlong, $6 million renovation paid for through proceeds from the National Lottery and from the Churches Conservation Trust, which is funded by the Church of England and the British government.

The restored church, which had been shuttered for more than a decade, was leased to a nonprofit group that offers circus training to young people, Circomedia. Many of them come from the area around the church, which has high rates of unemployment, drug use, and crime.

“We haven’t abandoned this church,” Rev. Self said. “We’re just going to use it a little differently now.”