Thrivent Financial for Lutherans is reaching beyond its roots for the first time, opening its membership and services to all Christian faiths.

The financial services firm confirmed Thursday that its members supported expansion by a margin of 72 percent to 28 percent. About 425,000 members — 21 percent of Thrivent’s total membership — voted on the measure, a higher participation rate than executives had expected.

The decision to redefine the organization’s “common bond” struck at the heart of the not-for-profit institution, whose roots go back more than 100 years.

“People tend to be looking for a good church probably more than a specific type of church,” said Brad Hewitt, Thrivent’s president and CEO.

Thrivent is a fraternal benefits organization based in Minneapolis that sells insurance, annuities and other financial services to its 2.5 million Lutheran members. For years, the Fortune 500 firm has wrestled with whether to extend its reach beyond the Lutheran faith, amid declining loyalty to church denominations. The number of practicing Lutherans is shrinking as younger generations consider other faiths.

The results of the member vote is a response to the reality that “brand loyalty to denominations” isn’t what it was in first-generation immigrants, Hewitt said, adding that executives didn’t know what to expect when they opened the question to a vote.

“We hoped we would at least get two-thirds, so 72 percent is obviously better than we hoped,” Hewitt said.

The change won’t be immediate and is more likely to start at the beginning of 2014, the company said. Currently, a person must either be Lutheran or married to a Lutheran to be eligible to join Thrivent. Membership is also open to people who attend a Lutheran school, such as St. Olaf, or who work for a Lutheran organization such as Lutheran Social Service.

Thrivent will continue to use the short version of its name for marketing, while the legal name of the organization will remain Thrivent Financial for Lutherans. Any change to the legal name would require a member vote, which is not planned.

Hewitt said Thrivent’s mission is to help Christians be wise with money and live generously, and the vote will allow it to serve more people.

As news of the results began circulating, a few Thrivent members expressed their objections on the firm’s Facebook page. “I am disappointed in the vote. This was an organization for Lutherans and you are now throwing away that identity,” Jim Robbins posted. “I will be moving my money out of Thrivent.”

Hewitt said it is difficult for some to let go of “our own special little thing,” but the change does not mean Thrivent is abandoning current members.

“That fear of abandonment is a legitimate fear, but I don’t think it will be true,” he said.

Jane Wilke, 59, who works for Lutheran Senior Services and lives in both Woodbury and St. Louis, Mo., said she thinks Thrivent is gaining “a bigger blanket of ministry,” and not losing its Lutheran identity.

“We haven’t lost our roots. We haven’t lost our legacy. We are just broadening the audience who receives the benefit,” she said in an interview. “I’m very excited.”

Equal parts faith and finance, Thrivent has maintained a church club feel. The corporate headquarters in downtown Minneapolis has a chapel for prayer and reflection, and holds Advent and Lenten worship services typically led by a Lutheran pastor, with an employee choir belting out hymns.

A gallery displays religious art from the 1400s to the present.

Meetings of the board of directors kick off with an invocation/devotion broadcast for employees over the PA system.

As a tax-exempt fraternal benefit society, Thrivent is required to have a “common bond” membership theme that excludes certain groups. That Lutheran common bond now gives way to a Christian one.

Thrivent produces annual revenue of more than $8 billion and has more than 2,000 financial representatives who provide members a full range of banking, investment and insurance products.

Thrivent doesn’t report profits per se. But its total surplus, an accumulation of internally generated earnings, rose 13 percent last year from 2011 to an all-time high of $6.1 billion. That was its strongest growth since 2006, and the company called it one of the best years financially in its 111 years.