SALEM — Two of the North Shore’s oldest churches will officially become one on Sunday, Sept. 13.

Members of the First Parish Unitarian Universalist Church in Beverly and the First Universalist Society of Salem plan to meet on Veterans Memorial Bridge to formally sign the merger agreement, then head to Beverly for their first combined service at First Parish.

“We’re very excited,” First Parish minister Kelly Asprooth-Jackson. “It’s a big moment in the history of both congregations.”

The merger marks the end of First Universalist, which was founded in 1805 and has been based at its Federal-style church at 211 Bridge St. since 1808.

First Universalist member Patti Welch, who served as co-chair of the merger committee, said the church began seriously looking for a partner two years ago as membership continued to decline. As of last count, the church had just 39 members.

“It just became very obvious that we were going to run out of money,” Welch said. “It was very difficult. It was very emotional.”

Welch said First Universalist was hit by the same societal forces that are affecting many congregations.

“Across the board people are very busy and they don’t have the time for a set Sunday service anymore, and they don’t want to put in the time,” she said. “People are using different tools other than religion to sustain their own spiritual health.”

First Universalist also had discussions with the First Church in Salem, as well as with Unitarian churches in Marblehead and Swampscott, before working out a partnership with First Parish, the oldest church in Beverly. First Parish was founded in 1667, before the city was incorporated.

Asprooth-Jackson said First Parish leaders and members explored the merger process “with a sense of neighborliness.”

“They’re our closest Unitarian-Universalist neighbors by distance,” he said. “We looked at questions like, ‘Does their congregational culture match us?,’ ‘Are our worship styles and styles of leadership complementary?’ After spending time getting to know each other, it seemed like that was the case.”

As Unitarian-Universalists, Asprooth-Jackson said both congregations are “open and accepting communities.”

Asprooth-Jackson said First Parish, which has about 175 members and an annual budget of around $220,000, is financially sound and wanted to make sure it would not be taking on any debt in the merger. That was assured when First Universalist transferred ownership of the church to The Bridge at 211, nonprofit formed by church members and community leaders to take over the building.

Bridge at 211 board member Dale Yale said the new organization wants to transform the building into a community center that will include partnerships with music and theater groups. The building will also serve as the permanent home of the Salem Food Pantry.

“It has lovely, historic McIntire carvings and a beautiful antique organ,” Yale said. “We feel like it’s kind of a hidden gem in the community, so we’ll try to find a way to make it more visible and more a part of the greater Salem community.”

The Bridge at 211 plans to hold a ribbon-cutting and open house in November.

Some First Universalist members have been attending First Parish’s summer services at Dane Street Beach in Beverly. Sunday’s service will be the first at the First Parish Church on Cabot Street.

Before the service, the merged congregation plans to meet at First Universalist in Salem, then head to Veterans Memorial Bridge to formally sign the merger agreement.

“It’s symbolically connecting the two congregations,” Asprooth-Jackson said. “We’re kind of meeting each other halfway.”

Staff writer Paul Leighton can be reached at 978-338-2675 or pleighton@salemnews.com.