St. Gregory of Nyssa Episcopal Church on Potrero Hill was in high gear this week with the annual frenzy of Holy Week that starts with Palm Sunday’s hosanna singing and doesn’t let up until Easter Sunday’s post-service picnic.

But along with the normal pageantry and prayer, this year’s activities are overshadowed by something the parish isn’t normally involved in: San Francisco land-use politics.

A developer wants to build a 17-unit condo building on land just south of St. Gregory’s, a shingle-clad church that, while only 21 years old, attracts architecture buffs from around the country and parishioners from as far as away as Santa Cruz and Santa Rosa.

The condo project, at 540 De Haro St., would replace a two-story warehouse that is home to a Moto Guild, where motorcycle enthusiasts can learn to fix their bikes. While the proposal is relatively small, parishioners say it would have a big impact on the church, blocking nine south-facing windows that fill the sanctuary with dramatic rays of sunlight.

Burton Edwards, a St. Gregory’s parishioner and Berkeley architect, said the rays of sunlight are “absolutely magical and an important part of worshiping” at the church, which is big on congregational dancing and participation.

“You come in and the light is so bright for a moment you are blinded as you walk in singing and dancing,” Edwards said.

On the surface, the land-use spat is no different from others unfolding in the mixed-use part of the city that stretches from the Mission District through Potrero Hill to Dogpatch.

On the one side, there is a seasoned developer proposing a well-designed residential building consistent with zoning that adds badly needed housing to the city’s stock. On the other side, you have neighbors who say numerous new projects are destroying neighborhood character by wiping out blue-collar jobs and catering only to the rich.

Striking architecture

St. Gregory’s opened in 1995 across the street from Anchor Brewing Co., well before Potrero Hill started attracting upscale condo residents and the cafes and Whole Foods that opened to serve them. The church’s architectural style is an ecumenical amalgamation of motifs and iconography — exposed beams, Japanese shrines, a Zen garden and a lofty cupola that rises 60 feet above the altar.

The rotunda that is illuminated by the south-facing windows is decorated with depictions of 90 dancing saints like Francis of Assisi and also characters like poet Emily Dickinson, jazz saxophonist John Coltrane, architect Julia Morgan and Supreme Court Justice Thurgood Marshall. With maple floors sprung for dancing, the rotunda doubles as parish hall and distribution center for a weekly food bank that attracts 400 people.

The church’s rector, the Rev. Paul Fromberg, said the parish isn’t opposed to development and that St. Gregory’s has been a good neighbor to the businesses that have come and gone from 540 De Haro, which previously housed a bicycle repair shop.

“We blessed the motorcycle shop,” he said. “We did a procession over there with incense and holy water. The guy was like, ‘Can you go to the other room, too? I’ve got a couple of bikes there that aren’t working.’”

He said it’s no surprise that the warehouse would attract a housing developer.

“We’re OK with that. We’re all for having neighbors, although we wish it were not just housing for rich people,” Fromberg said. “But the fact that it obstructs the light of one of the most beautiful public buildings in the city is a problem. A church is a place for anyone to come. You don’t have to believe anything or pay anything or do anything. You just walk in the doors.”

The last-minute objections came as a surprise to the developer. In January, the project, which has been in the planning pipeline for more than two years, was set for approval when suddenly church members showed up in force at a Planning Commission meeting to oppose it. Nobody from the church had attended prior meetings about the project, according to the developer.

Project architect Mitchell Benjamin of Sternberg Benjamin said the church was notified, along with the rest of the neighborhood, when the project started. In 2014, Benjamin said, he spent a day at a table outside the property showing the plans to anyone who was interested.

“We would have been very happy if they had approached us two years ago to discuss the issues,” he said.

Design criticized

Benjamin said the St. Gregory’s complaints are driven by what he sees as a design flaw in the church: Those light-catching windows are just 5 feet from the property line shared with 540 De Haro.

“Why would you put your most important window alongside a property line?” he said. “Why wouldn’t you make damn sure that the windows would not be on the property line but street-facing or near the center of the property, so that nothing would ever be built near it?’’

So far, planning commissioners seems to be listening carefully to the church’s objections. The project seemed to be cruising toward approval until the Planning Commission voted 6-1 in January to continue it. Commissioners asked the two sides to work out a compromise.

“I am a strong believer that light is a spiritual aspect in religious architecture,” said Commissioner Kathrin Moore. “There are reasons why we go to places of worship, and light is a key ingredient in what we do there.”

Commissioner Rodney Fong called the church a “beautiful, one-of-a-kind space.”

Only Commissioner Christine Johnson voted against delaying approval.

“I don’t see a lot of reconciliation possible,” she said.

So far Johnson seems to be right: There is no compromise after two meetings. The developer offered to carve about 10 feet out of the top floor unit closest to the church windows, but St. Gregory’s says that wouldn’t help much and is asking for 30 feet.

“These guys haven’t been in any way generous in trying to respond to us,” said Edwards, the parishioner.

Loss of 3 units

Benjamin said meeting the church’s demands would cut three units out, making the development financially unfeasible.

“Is the priority in San Francisco to build as much density as possible, or is the priority to protect a property-line window?” he said.

Benjamin said the church could do several things to help bring in more direct sunlight. It could remove the eaves on the cupola or cut a new skylight into the domed room. He said he is willing to pay for the changes.

“My client was willing to live with the pain of losing a unit, but is pretty unhappy that (the church) still wants more and is unwilling to look at their own building,” he said.

St. Gregory’s Director of Ministry Sara Miles said the church is eager to resolve the conflict but not willing to see its sunlight blocked.

“This is a well-known destination for architects and pilgrims and ordinary citizens,” said Miles. “It’s a holy place for everyone to use. The doors are always open.”

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jdineen@sfchronicle.com Twitter: @sfjkdineen