For years, architects, engineers and Barcelona residents have been sounding the alarm: the Expiatory Temple of the Sagrada Familia, Gaudi's unfinished modernist masterpiece and Spain's top tourist site, could be endangered by a government plan to build a high-speed rail tunnel only 13ft (four metres) away.
Residents hung protest banners from windows. The architect in charge of turning Gaudi's blueprints into undulating, ceramic-coated reality called the tunnel "an attack on culture of the highest order".
Activists filmed a simulation of the 20,000-tonne building's collapse, its spindly, twisting towers and exuberant sculptures turned to dust. The digging started in March, nevertheless.
Now the worriers have won a small victory. The Spanish parliament has voted to suspend construction "immediately" as a cautionary measure while independent experts devise an alternate train route that would link Barcelona with the French border without jeopardising the work of "God's architect", which is soon to be consecrated by the Pope.
"The government should reconsider what it is doing," said Joan Rigol, chairman of the Sagrada Familia Foundation, which aims to finish the church Salvador Dali once called a "tactile erogenous zone" by 2025.
"The whole world thinks that there is a danger to the monument."
The vote is non-binding, but it exerts extra political pressure on the already beleaguered Socialist government of Jose Luis Rodriguez Zapatero.
Following the vote, a spokesman for the Ministry of Public Works vowed that construction of the rail tunnel will continue with rigorous security measures, which include an underground protective barrier only 7ft (2.1 metres) from the Sagrada Familia's foundations.
The minister, Jose Blanco, told parliament that starting from scratch with an alternate route would be too expensive and would delay Spain's high-speed link with the rest of Europe for two years.
"What good is democracy if the government ignores the will of the people?" said Pere Vallejo, head of the citizens' platform against the tunnel, after the vote.
Mr Vallejo's group is not only concerned with the future of Gaudi's work of art. He's also worried about the fate of the 18,000 flats, like his own, that are also in the train tunnel's path.
Faced with the government's intransigence, the 80,000 members of the international Gaudi Beatification Society might pray to the architect for miracles. After all, the monk-like Gaudi, who died not as a martyr but as a victim of a traffic accident in 1926 at the age of 74, is considered a strong candidate for sainthood, his sensual rendition of the gospel seen as a tool to convert non-believers.
But the Sagrada Familia Foundation isn't waiting for divine intervention. It is about to file its sixth official complaint in the Spanish High Court in the hope a judge will order construction to halt permanently.
Sagrada Familia architects and engineers fear that tunnel construction could shift the "slippery, sandy" ground beneath the church, which could cause part of the building to sink and lead to cracks, Mr Rigol said.
The vibrations of a bullet train could also damage the prized monument, a Unesco cultural heritage site that attracts three million visitors each year, especially Japanese tourists, the major donors to the church construction.
"Gaudi built without buttresses," he said.
"The roof is made of many small stones, a technique know as trencadis, and any light movement could cause a great deal of damage."
A recent report by the International Council on Monuments and Sites praised the project for following EU technical and security standards, but called for an independent structural study of the building's foundations and urgent meeting between the Spanish government and Unesco heritage experts.