The Vietnamese government continues to face petitions from Catholics over properties confiscated by the government after 1954, the Associated Press reports.
However, improved church-state relations have meant the Vietnamese government has not cracked down as harshly as it has in the past.
Catholics have focused their prayers and pleas on the old Vatican embassy, a 2.5-acre lot in central Hanoi worth millions.
"It is a tragedy for us that our holy land was taken away," said Father Nguyen Khac Que, a priest of the Hanoi diocese who helped organize the prayer vigils.
Church officials say they have documentation showing the property belongs to the diocese. Government officials claim a former priest voluntarily turned the land over to them in 1960.
"This whole matter of returning land is very complicated," Duong Ngoc Tan, of Vietnam's national Committee for Religious Affairs, told the Associated Press.
Only five years ago, the public prayer vigil of the protesters would probably have led to jail time.
"There is now a sufficient feeling of comfort on both sides that the church feels it can air its grievances publicly and the state feels it can tolerate them," said Peter Hansen of the Catholic Theological College in Melbourne, Australia, speaking to the Associated Press.
Despite city officals’ requests to stop the protests, church leaders plan their biggest vigil yet for this Friday. Because public protests are generally forbidden, leaders are careful to refer to the gatherings as vigils, rather than demonstrations.
Pham Vu Thuc, a lay Catholic in Vietnam, said globalization had caused the Vietnamese government to become more attentive to global standards of religious freedom.
"Things have changed a lot since we've become more connected with the outside world," she told the Associated Press. "We have the Internet, we've joined the World Trade Organization. Now Vietnam has to follow the rules of the international community."
According to Independent Catholic News, thousands of California Catholics have been holding prayer vigils in solidarity with their fellow Vietnamese Catholics. Two thousand attended a candlelight vigil and Mass at St. Maria Goretti parish in San Jose, California, praying for the Vietnamese Catholics’ effort.
There are six million Catholics in Vietnam, a predominantly Buddhist country.