More than 40 years ago, when Father John Powis was studying to be a priest, he stumbled into an opportunity that would define the rest of his life. “I had never had any contact with a black or Hispanic person before,” remembers Powis, who grew up in nearby East New York. So he spent a few summers, without pay, working with nuns ministering at a housing project in Fort Greene, Brooklyn. “I got to know every single family who lived there, inside and out,” he says. “That right there was 85 percent of my education.”

Today, Powis, 69, heads up St. Barbara’s Roman Catholic Church in Bushwick, which draws 1,600 predominantly Hispanic congregants to the regular Sunday mass.

From his first days as a priest, he has embraced community activism: He joined local parents in battling for community control of the public schools in the late 1960s. A decade later, he helped found East Brooklyn Congregations, a coalition of churches that has built thousands of inexpensive homes in nearby Brownsville and East New York under the Nehemiah program. And a few years ago, he rallied hundreds within the community to successfully protest the city’s plan to remove fireboxes from sidewalks across the five boroughs.

Along the way, Powis hasn’t been afraid to bump heads with–and even tear into–local politicians. Perhaps his most frequent target is powerful Bushwick state Assemblymember Vito Lopez. “I don’t believe in what he’s doing,” says Powis, who condemns Lopez for often channeling state funds and development projects to a nonprofit group that Lopez founded.

Lopez, 61, an assemblyman for 18 years, touts his own political record of building affordable housing, and brushes off Powis’ critique. “The community would be better if Father Powis would work within our organized political structure, but he doesn’t, so conflicts exist,” he says.

Father John Kelly, the priest at nearby St. Brigid’s, says Powis is a major figure in Bushwick because he has proven his ability to rally the masses. “The establishment has always been afraid of him,” says Kelly. There was a time when, if trouble arose, “You’d call Powis, not the police, because he’s just that much more influential and he knows how the system works.”

The round-the-clock work is draining for Powis, and he says health problems may soon force him to retire. But, he adds, it will take strict doctor’s orders to do that. “If the doctor tells me I have to, I will,” he says. In the meantime, he plans to continue the work that has kept him going for 43 years. “I’m so grateful I’ve been able to give the poor people hope that life can improve,” he says. “They don’t know it, but they’ve done the same for me.”