In December 1992, Phil Saviano was at the lowest point of his life. He was 40 years old, out of work and dying of AIDS. Leafing through the Boston Globe, looking for some last-minute Christmas gifts, he saw a small item that contained a familiar name.

He read that a Catholic priest, David A. Holley, had been arrested for abusing boys in the 1970s at a church in New Mexico.

“It was a life-changing moment,” Mr. Saviano later told the British newspaper the Daily Mail. “It was the day all the bells went off for me. I suddenly saw how naive I had been in assuming he had only done this to me.”

Almost three decades earlier, beginning when Mr. Saviano was 11, he had been repeatedly molested by Holley at St. Denis Catholic Church in Douglas, Mass. The abuse went on for a year and a half, until Holley left the parish.

With a strength born of desperation, Mr. Saviano found his voice and told his story to the Globe, becoming one of the first victims of sexual abuse by a priest to go public. In 1995, he reached a financial settlement with the diocese of Worcester, Mass., that amounted to $5,700 after attorney fees. He turned down a larger payout that would have required him to keep silent about his childhood trauma. He believed the only reason he didn’t have to sign a confidentiality agreement was that no one expected him to live.

“If I had not been dying of AIDS, I would not have had the courage to come forward,” Mr. Saviano told the Globe in 2009, “but at that point my career was over, I was on my way out physically, my reputation was shot in the eyes of many people, and I didn’t have a lot to lose. This was a final opportunity to effect some change and address this thing that happened to me when I was a kid.”

Soon afterward, he received a new HIV/AIDS treatment that helped him regain his health. He found a new sense of purpose as an activist and whistleblower and began to research sexual abuse in the Catholic Church. In 1997, he founded a New England chapter of the Survivors Network of Those Abused by Priests (SNAP).

With a background in public relations, Mr. Saviano approached the Globe with his evidence in 1998, but the paper passed on the story. But beginning in 2002, under a new editor, Martin Baron (later the executive editor of The Washington Post), a group of Globe investigative reporters called the Spotlight team published a series of stories detailing predatory behavior by dozens of Boston-area priests, coupled with a concerted effort by top church officials to conceal their misdeeds.

The Globe won the Pulitzer Prize for its articles, which formed the basis of the 2015 film “Spotlight,” in which Mr. Saviano was portrayed by actor Neal Huff, who became a close friend. Mr. Saviano advised writers on the screenplay and was onstage at the Oscars, along with the film’s director, producers and actors, when “Spotlight” won the Academy Award for best picture. (It also won for best original screenplay.) Executive producer and co-writer Josh Singer called him a “true hero.”

Mr. Saviano was 69 when he died Nov. 28 at a brother’s home in Douglas. He had announced on his Facebook page in October that doctors could no longer treat his gallbladder cancer. In the preceding months, he had also had heart surgery and a stroke. The death was confirmed in a statement by his brother Jim Saviano.

After speaking out, Mr. Saviano channeled his harrowing childhood experience into an effort to address wrongdoing in the church. By the time the Globe began its investigation, he had already identified 13 predator priests and hundreds of victims in the Boston area. When he examined church documents, he learned that many of the priests had been transferred to other parishes around the country without being punished. (The number of priests accused of sexual assault in New England eventually grew into the hundreds.)

Initially, as a gay man challenging the authority of the Catholic Church in the early 1990s, Mr. Saviano faced a backlash from church loyalists and even from members of his own family. His father “was angry and accused me of bringing the scandal to our hometown,” Mr. Saviano later said.

During his childhood in Douglas, a small town about 55 miles from Boston, Mr. Saviano enjoyed fishing and hiking. He also delivered newspapers, and one of the stops on his paper route was the rectory of St. Denis Church, where Holley had been newly installed as a priest.

Then in his 40s, Holley was popular with boys in the church, showing them card tricks and making faces behind the backs of nuns teaching Sunday school. When the priest asked Mr. Saviano and another boy to help move boxes of hymnals or do other odd jobs at the church, they felt honored. They received 50 cents apiece.

“He was grooming us,” Mr. Saviano told the Daily Mail in 2015. “The priest figures out ways to get closer to either the child or the parents. That gives him an opportunity to know what is going on in our family and in school. I felt pretty lucky that this guy was taking an interest in me. For us, he was God’s representative on earth, who could perform magic like turning wine into the blood of Christ and forgiving sins.”

Then one day when Holley was doing card tricks, the deck of cards contained pornographic images of people engaged in sex acts. When the 11-year-old Mr. Saviano tried to run away, the priest grabbed his wrist and held him back. Years later, Mr. Saviano could still recall “the coolness of the dark church basement, the smell of his sickly, sweet cologne” and “the sense of being completely trapped.”

Over the next 18 months, Mr. Saviano was repeatedly coerced into performing sexual acts on Holley. The priest once assaulted him behind a door as parishioners walked past, just feet away. Another time, Mr. Saviano saw the priest forcing himself on another boy at the church altar.

“How do you say no to God?” Mr. Saviano’s character says in “Spotlight.”

Mr. Saviano did not speak of his experiences until he was 40. Holley, in the meantime, went on to work at churches in New Mexico, Texas and Colorado before receiving a 275-year sentence in 1993 for the sexual assault of eight boys in New Mexico. He died in prison in 2008.

The Globe’s revelations, made possible in part by Mr. Saviano’s research, shocked people around the world and reverberated throughout the Catholic Church. One of the church’s most powerful figures, Cardinal Bernard F. Law of Boston, admitted that he had reassigned priests accused of child abuse and did little to stop the scourge. He resigned in 2002.

“Finally, victims are being first of all believed,” Mr. Saviano told the Globe that year. “And they’re being respected instead of ridiculed and criticized. Most of all, they’re seeing there is power in joining together and speaking out, and you can have results. Laws are being changed, [attorneys general] have perked up their ears around the country. These are changes that victims, myself included, could only have dreamed of.”

Philip James Saviano was born in Douglas on June 23, 1952. His father was an electrician, and his mother was a homemaker.

Mr. Saviano majored in zoology at the University of Massachusetts at Amherst, from which he graduated in 1975. He settled in Boston and received a master’s degree in communications from Boston University in 1980. He worked in public relations and fundraising for a Boston hospital and later had a concert production company from 1982 to 1991. He also collected and sold Mexican folk art.

His survivors include three brothers.

In addition to forming a New England chapter of SNAP, Mr. Saviano ran the organization’s national website for several years and served on its board of directors. He was also on the board of BishopAccountability.org, which documents sexual abuse in the Catholic Church. He traveled widely to give speeches and counsel other survivors. He appeared at the 2019 Vatican summit on sexual abuse in the Catholic Church.

“Every step they’ve taken,” he said of church leaders, “they’ve done it begrudgingly.”

Mr. Saviano’s experiences with the church caused him to lose all religious faith, and he considered himself an agnostic.

“I find myself envious sometimes of people who do have a strong faith,” he said in 2002. “And I don’t know what that’s like. There are days when I can’t do this on my own.”

Mr. Saviano received a diagnosis of AIDS in 1984, then in 2009 learned that he needed a kidney transplant. When no one in his family was a proper match, he asked for help from the network of survivors of clergy abuse. Several people volunteered, and he ultimately received a kidney from a Minnesota woman who said she had been sexually abused in high school by a former nun.

Among people who had been victimized by priests and church leaders, Mr. Saviano was seen as a valiant, eloquent and courageous champion who refused to be silenced. He also found respect closer to home and, at long last, had a warm reconciliation with his father.

“All those years ago,” his father told him, “you were right. Give them hell.”