For Newcastle’s St. Patrick’s parishioners, the old and the new are a match made in heaven.

Disbelievers thought it couldn’t be done, the Rev. Raymond Picard said Wednesday, showing off the parish’s new $2 million church.

In the beginning, some members couldn’t imagine another church attached to the rear of the oldest Roman Catholic church north of Baltimore. They vowed not to part with the old church and have it simply become a museum.

So they came up with a distinctively Maine solution: They kept both as churches.

In Maine, “The barn’s always attached to the house,” Picard said.

The attractive arched windows and tarnished copper roof of the new church blend with the curved stained glass and cedar shingle counterparts of the old church.

“One thing people insisted on,” Picard said. “They wanted lots of windows.”

Now, the new church hosts weekend Masses, and the old church is used for daily Masses and Communion services.

Last Sunday, 500 people attended Mass to dedicate their newest place of worship.

The red brick church built in 1808 on a foundation of massive granite blocks served the parish well until about a decade ago when the dozen pews on each side of the aisle started to get crowded. The seating capacity is 110.

In the 1780s, St. Patrick’s first priest, the Rev. John Lefebvre de Cheverus, came to the Damariscotta Mills church just two months of the year. Cheverus, a traveling priest served similar stints in Boston, parts of Maine, and occasionally Portsmouth, N.H.

Although St. Patrick’s was built in 1808, the first resident priest did not arrive until 1928. Picard likes the name of the original Damariscotta Mills Catholic chapel: St. Mary’s of the Mills, which he said disappeared when St. Patrick’s was built.

In the past nine years, St. Patrick’s membership has grown threefold, to 440 families, Picard said. At first, Masses moved into the parish hall next to the church, accommodating 235 people. That, too, started getting crowded.

Some parishioners also noted a need for the church to be accessible to the handicapped. Picard noted that plans for the new church include an elevator and room for expansion.

One church member became “the devil’s advocate,” asking why St. Patrick’s needed a new church, Picard said, explaining they would have to offer the higher-ups good reason for requesting construction. Parishioner growth was the answer.

Initial consultations with architects placed the estimated cost of construction at $4 million, which was later trimmed to $3.5 million. Still, parishioners found that cost beyond reach.

Then one day, parishioner and builder George Hervochon of Damariscotta arrived with design plans under his arm for a building that would cost $2 million. Then-Bishop Joseph Gerry waived the usual requirement for an architect, and Hervochon was hired as the contractor.

In just two years, the parish has raised most of the money needed to build the church, which is not quite finished. There’s also plenty of sweat equity in the walls and wood ceilings.

Deacon Martin Fallon, 84, painted new Stations of the Cross for the church. Another parishioner donated all of the trees and shrubbery for landscaping.

The first phase is nearing completion, but another $175,000 is needed to finish the work, which includes complying with a state Department of Environmental Protection requirement to shore up an eroding bank behind the church.

Another $300,000 would pay for the second phase, which involves a new parish hall in the basement that would seat 350, complete with a kitchen and restrooms. The hall would “serve the community” for various occasions, Picard said, and could be a source of revenue.

Eventually, the old parish hall will be converted into classrooms for religious education.

“As we have the money, work is done,” he said. “Rome wasn’t built in a day.”