BALTIMORE - The process of recognizing saints in Catholicism is so arduous that it can take generations, even centuries, to complete, but even the usually slow-moving Catholic church can accelerate matters when it wants to.

In the cases of Mother Teresa of Calcutta and Pope John Paul II, for example, church officials waived a five-year waiting period after their deaths to get the process started.

Now a group of Baltimore Catholics says it’s time to expedite the cases of six other heroes of the faith.

Parishioners of St. Ann’s Catholic Church, a predominantly African-American congregation in the East Baltimore Midway neighborhood, and the two other churches in its pastorate, Historic St. Francis Xavier and St. Wenceslaus, seek to make the case that the church should immediately canonize six Black American Catholics. The candidates include Mother Mary Lange, a Baltimore nun who started and ran a school for Black children during the era of slavery.

They used a special Mass at St. Ann’s Monday night to advocate for the cause, and organizers said they’ll also use the All Saints’ Day service to launch a national letter writing campaign. They hope to collect signatures on letters from Catholics across the Archdiocese of Baltimore and beyond in the coming weeks, then bundle them into a package to send to Pope Francis no later than January.

Mother Lange, who died in 1822, and the other candidates—including a Haitian Ameri- can former slave, Pierre Toussaint, who went on to became a successful business owner and philanthropist in New York, and the Mississippi- born scholar-evangelist Thea Bowman—had to overcome so much racism inside and outside the church during their lives that their cases should be viewed as exceptional, said Ralph E. Moore Jr., a St. Ann’s member helping to lead the effort.

The church has never made a Black American Catholic a saint.

“These strong and courageous people lived exemplary lives,” said Mr. Moore, a lifelong Catholic who is African-American. “They kept the faith through slavery and other forms of racial discrimination, even when they were considered second class members of their own church.

“The church has broken the rules (for the canonization process) before. It could do the same again. We believe it should,” he contin- ued. “We’d like to see these ancestors of ours be canonized.”

The Mass included a procession into the church by parishioners carrying oversized portraits of the six candidates for sainthood— Mother Lange, Mr. Toussaint, Ms. Bowman, the Rev. Augustus Tolton, Julia Greeley and Sister Henriette DeLille—as a three-church choir sang, “When the Saints Go Marching In.”

Rev. Tolton, a former slave who was bap- tized and raised Catholic, was rejected on the basis of his race by every American seminary he applied to. He went to Rome to study and, in 1886, won the distinction of being the first Black priest in America. (The racial background of three brothers ordained earlier was not widely acknowledged during their lifetimes. James, Patrick and Sherwood Healy were the sons of a Black woman who had been enslaved and the white man who owned her, according to an essay by James M. O’Toole, a professor of history at Boston College.)

Ms. Greeley, who was born enslaved in Missouri in the mid-1800s and baptized Catholic, became known as Denver’s “Angel of Charity” for her work on behalf of that city’s poor.

Sister DeLille, a Black nun from New Or- leans born in 1813, opened the first Catholic home for older adults and founded an order of women religious in the face of opposition due to her race.

The process of declaring a person is a saint involves several major steps. Five years or more after candidates have died, their bishop can open an investigation to determine whether their life was sufficiently holy or virtuous. If a special Vatican department, the Congregation of Saints, agrees, the candidate is deemed a “Servant of God” and the case moves forward.

If church researchers can verify one miracle the candidate has performed, he or she is “beatified,” and a second confirmed miracle can mean sainthood.

All six have been declared Servants of God, meaning they’ve passed the first major test along the road to sainthood. Mr. Toussaint, Rev. Tolton and Sister DeLille also have been deemed “Venerable,” placing them one miracle shy of beatification.

Saints are thought to live near God in heaven, to be able to intercede with God and to be exemplars of godly behavior. That means the absence of an African-American saint leaves a gap in the spiritual lives of 3 million Black Catholics in the United States.

Some in the archdiocese see the fledgling push as comporting with a larger effort on the part of the modern church to acknowledge, attempt to atone for and transcend a history that few modern observers would deny has long been stained by racism.

Bishop Bruce Lewandowski, longtime pastor of the predominantly Spanish-speaking Sacred Heart of Jesus Church in Highlandtown and now urban vicar for the archdiocese, concelebrated Monday’s Mass with the Rev. Xavier Edet, leader of the St. Ann’s pastorate.

Bishop Lewandowski points out that priests, bishops, deacons and nuns of generations past were themselves among the Americans who enslaved people. Their attitudes became baked into the foundations of a faith whose seminaries often excluded Black students, whose hospitals often barred Black patients and whose congregations sometimes made Black worshippers sit in the back pews—when they were admitted at all.

Mr. Moore, 69, grew up in a day and age when some of those practices were in effect.

When he attended predominantly white Catholic churches as a boy, he said, his family had to sit in the back three rows. It was required that white worshippers take communion before African-Americans, he said.

Such slights confused a young man who was otherwise enthusiastic about his faith, especially the exceptional education he received in Baltimore’s Catholic schools.

“You can’t love the Gospels and treat people badly, but this church would somehow allow people to practice Catholicism and racism at the same time,” he said.

Though the church eliminated those strictures over the years, progress in other areas came slowly. It took the Black Catholic Movement of the 1960s and 1970s to press the case for ordaining more Black Catholic priests and bishops, for example. It was not until last November that the church raised an African-American prelate, Archbishop Wilton Gregory of Washington, D.C., to the rank of cardinal.

Delores Moore, who is not related to Ralph Moore, is another longtime parishioner at St. Ann’s and, like Mr. Moore, is a member of its social justice committee. She said it has long been painful to face the fact that out of the more than 10,000 men and women the Catholic church has canonized in its history—including dozens of individuals of African descent, 11 Americans and a record 899 by the current Pope Francis— not one is African-American.

“It has always been an important issue,” said Ms. Moore, who is African-American. “But given what’s happening in our society with Black Lives Matter, the injustices we’ve seen with George Floyd and all the other less- publicized injustices that happen every day, we’re becoming aware that systemic racism happens throughout our society, and that, unfortunately, includes our churches.

“Maybe it’s unintentional,” she said. “I hope so. But we need to put a spotlight on this.”

Mr. Moore said they’ve waited long enough, that the church should waive its usual requirements and recognize them as soon as possible as the saints they are.

“The church keeps saying, ‘We’re following the process.’ But if the process produces bad results, maybe the process needs to be recon- sidered,” he said. “We’re asking them to put these six on the fast track.”