BANGOR, Maine — When the Rev. Becky Gunn was hired by the Unitarian Universalist Society of Bangor six years ago, she had one thing in common with one of her predecessors who had served the Park Street church in the mid-19th century.

Gunn, like the Rev. Amory Battles when he was hired in 1851, did not perform weddings.

Battles did not perform weddings until after the Emancipation Proclamation was issued in 1862, because to be licensed by the state to marry couples, he had to swear an allegiance to the U.S. Constitution, which sanctioned slavery.

On the other hand, Gunn refused to officiate at any marriage ceremonies until same-sex couples were given the legal right to marry in Maine.

When she was interviewed for the job, Gunn told the hiring committee: “I would not marry anyone until I could marry everyone.”

Gunn, 66, retired June 30, just one month shy of her starting date of Aug. 1, 2008. She said in mid-June that health issues were the reason for retirement, and she planned to return to the West Coast, where she has lived most of her adult life.

“I’m no longer able to give the 110 percent required for ministry,” she said.

In assessing her impact on the church and the community, Gunn said she would like to be remembered for her very public role in the campaigns for same-sex marriage in 2009 and 2012.

“Those were intense times, and I think my leadership was important,” Gunn said. “When we ultimately passed the law — to be able to have all people marry — it was so wonderful for me.”

Her only disappointment was that since voters approved same-sex marriage in November 2012, she only performed about a dozen weddings.

“Not as many as I’d hoped,” she said.

The Rev. Sue Gabrielson, the executive director of the Religious Coalition Against Discrimination in Maine and the former faith director for the Marriage Equality campaign, said last month that Gunn and her congregation “made a huge contribution to the work we were doing, especially in the northern part of the state.”

“Becky and her church were instrumental in mobilizing people of faith,” Gabrielson of Yarmouth said. “She and her church folks went out and had one-on-one conversations that changed voters minds. She participated in every aspect of the campaigns from a faith perspective. She took a leadership role at trainings, rallies and pride events.”

Gunn said she also represented the church in progressive organizations, including the Peace and Justice Center of Eastern Maine, headquartered in Bangor, and Food and Medicine in Brewer.

Under her leadership, the congregation has not suffered the loss in membership other denominations have as Mainers have become more secular.

“We have grown about 10 percent,” she said. “The religious education program for children, however, has grown dramatically. We’ve gone from 20 to 25 children coming on a Sunday to now having a registration of about 90. That’s a strong program.”

Sue McKay, chairwoman of the church council, said last month that Gunn has involved members of the congregation much more in planning for and participating in worship services than they were prior to her tenure.

“Prior to her arrival, the minister pretty much did everything in the service,” McKay said. “She came in and said, ‘No, no, no. I really want to have more lay people in the service,’ and organized a program called the worship associates.

“That has made a very big difference, so that on a Sunday morning, there are more people in the pulpit taking important parts of the service, doing more than passing the collection plate,” she continued. “That makes the congregation feel more involved because they are more involved.”

Gunn called that “doing shared ministry.”

“I believe the minister is only part of the ministry of the church,” she said. “In order for there to be good ministry, the congregation has to participate. Now there is this very clear concept of ministry here.”

Gunn lived in Utah as a child and attended the Mormon church. As a young adult, she left religion behind for a 20-yearlong career in education and business in California. Eventually, she found a Unitarian Universalist Church in the Golden State where she felt comfortable. Gunn began to feel the call to ministry in 2001, and that fall, she entered the Starr King School for Ministry in Berkeley, California.

She replaced the Rev. Elaine Peresluha, who served as the congregation’s minister from 2000 to 2006. The Rev. J. Bradbury Mitchell of Brunswick served as interim pastor during the two-year gap.

During her tenure in Bangor, Gunn contributed to the faith column, “Voices,” published in the Bangor Daily News.

Shortly before she retired, the congregation voted to name her minister emeritus.

The Rev. Arthur Vaeni, a New Hampshire native, will serve as the interim minister for about the next year while a search is conducted for Gunn’s replacement.