BREWER, Maine — When the Rock Church applied for a permit to expand its North Brewer Shopping Plaza location in January, city officials discovered that churches are not allowed in the strip mall because of zoning.

Now the church is moving to Bangor.

“A church is not allowed in that zone: ‘convenience business,’” Ben Breadmore, Brewer’s code enforcement officer, said Monday.

Since the church has operated at the shopping plaza for more than three years, it is considered “a legal, nonconforming use. They could continue to operate as such. They just couldn’t expand,” Breadmore said.

Officials at the church and Dana Cassidy, the owner of the property, are upset about the expansion denial. Church leaders and Cassidy had agreed to a lease modification for the next four years that would have expanded the church’s space from around 4,500 square feet to 14,000 square feet.

“To me, that’s $100,000 a year,” Cassidy said Monday while sitting on a bench outside the Rock Church as workers inside removed items. “There is plenty of room to expand. We have 60,000 square feet.”

After the expansion request was denied, church officials had the option to file an appeal of Breadmore’s Feb. 17 decision but instead decided to move before their lease expires in April.

Still, Cassidy said he and church officials, through their attorneys, both sent letters to the city stating the expansion denial violated the Religious Land Use and Institutionalized Persons Act.

Under that federal law, “you can’t treat the church as a business,” he said.

Pastor Jim Funari, who has led the Brewer church for the last year, said it has grown so big it needs to expand.

“It’s crazy,” he said Monday, taking a break from moving items out of the Rock Church. “We had no idea we would have to move out.”

The Rock Church began in Bangor and opened a second location in Brewer in 2009.

“We’re going back to Bangor once our lease is up,” the pastor said.

In the near future, church members will start a capital campaign to build a 350- to 370-seat auditorium in Bangor near the Rock Church’s location on Ohio Street, Funari said.

“It’s sad to see it go. We put a lot of work in there,” he said of the Brewer church. “It’s home. It’s really not our choice to move.”

Both Cassidy and Breadmore said all involved worked together to try and find a solution but were bound by the city’s laws.

“These were set long before I got here,” Breadmore said. “Unfortunately, I can’t permit it. Nobody is kicking anybody out. They just can’t expand.”