At a time when many mainline Protestant churches in the U.S. are hemorrhaging members and struggling to stay afloat, St. Martin’s Episcopal, already the nation’s largest Episcopal church, is breaking ground on a $55 million expansion and renovation of its campus in Tanglewood.

That capital campaign — believed to be the most successful single capital campaign in the history of the Episcopal Church — is yet another sign that St. Martin’s continues to be that rarest of things in this era: a bastion of old-school moderation, calm and good manners, a traditional church that is, somehow, growing and thriving.

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St. Martin’s values were embodied by its most famous members: the recently deceased George H.W. and Barbara Bush — both of whom had funeral services last year at St. Martin’s, and both of whom were honorary co-chairs of the capital campaign. Other co-chairs included James A. Baker III, secretary of state during Bush’s presidency; and presidential son Neil Bush.

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So far more than 900 families have pledged to contribute. The amount of money raised is particularly impressive given that, in keeping with church tradition, none of the buildings will be named after donors, and the largest gifts receive no flashy fanfare. “It doesn’t matter whether you give $100 or $1 million,” said Rev. Russell Levenson, St. Martin’s rector. “Your name will be the same size on the plaque.”

Jackson and Ryan Architects, which designed the1,200-seat central church building completed in 2004, has also drawn up plans for the expansion project. A new Parish Life Center will house the church’s growing contemporary services, events such as concerts, and meetings for recovery and support groups such as Alcoholics Anonymous.

There’ll be a new Children’s Ministry Building; a new Music Building; and a new Pastoral Care Center to house the growing clergy team. The 1959 church building will become Christ Chapel, a 200-seat place for baptisms, funerals, weddings and other services.

As part of the expansion project, two campus buildings will be razed: a chiller at the corner of Sage and Woodway; and a building that once housed a bar owned by Sonny Bono, of the 1970s singing duo Sonny and Cher. The youth, Levenson said, have no idea who Bono was.

Tellepsen Builders, the same firm that constructed the 1959 church and almost all the other buildings on the campus, will handle the latest round, too. Tad Tellepsen says that in 1952, his grandfather and grandmother, June and Howard Tellepsen, were founding members of the church. St. Martin’s, he notes, had the luck to be founded at the right place at the right time — in the west Houston neighborhood soon to become the home to many of Houston’s most affluent people, as the oil industry made the city a magnet for growth.

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By the church’s tenth anniversary, its membership had grown to more than 2,500 baptized members. By its 50th anniversary, in 2002, it counted more than 7,000.

The current 9,500 members are now divided among six Sunday services: four traditional, two contemporary. “Of course, they don’t all show up every week,” Levenson laughs. “We’ll see them for Easter.”

Asked to explain his church’s success, Levenson referred obliquely to LGBT-related controversies that have rocked the Episcopal denomination — but also, more generally, to a way of existing in the world, a polite, thousand-points-of-light way of getting along.

“We don’t get caught up in church controversies,” he said. “We don’t talk about politics from the pulpit. We don’t obsess over the things that divide us. We focus on God’s love for us and His call for us to love one another.”

lisa.gray@chron.com