On Mother’s Day a year ago, I was staying in a house whose usual residents had gone to visit their mothers, leaving me alone to somehow cook a worthy breakfast for four extraordinary mothers—my own mother, my wife, a Venezuelan professor in exile and Elizabeth McAlister, the nun-turned-war-resister, an architect of the Plowshares movement with her husband, Philip Berrigan. This past Mother’s Day, Liz was in jail again.

Her offense was hardly surprising. On April 4 she was part of a small group that, much like the first Plowshares action in 1980, broke into a nuclear-armed military facility with hammers and bottles of their own blood in order to make literal the prophecy of Isaiah, “They shall beat their swords into plowshares.” The ritual was an evolution of the Berrigan brothers’ famous draft-card burning in Catonsville, Md., which took place 50 years ago this week.

This past Mother’s Day, Elizabeth McAlister was in jail again.

“Our apologies, good friends, for the fracture of good order,” Philip’s brother Daniel Berrigan, S.J., testified in court about that day in Maryland. “We could not, so help us God, do otherwise.” Such rituals have resulted in many collective years of jail time since.

The Berrigan brothers were on the cover of Time magazine after Catonsville. Some Plowshares actions have likewise garnered national attention, like the 2012 break-in at Tennessee’s Y-12 nuclear facility led by 82-year-old Sister Megan Rice. But this latest Kings Bay Plowshares break-in, at the Kings Bay Naval Submarine Base in Georgia, has been less widely observed outside the several hundred people awaiting news on a Facebook group. But I know some of the seven who participated, including Dorothy Day’s granddaughter Martha Hennessy, and I do not expect that they are worried about whether they are trending on Twitter. As Father Berrigan said, “We could not, so help us God, do otherwise.”

Our country’s nuclear weapons remain a clear and present threat to the survival of life on Earth.

A valuable new film by Helen Young, “The Nuns, the Priests, and the Bombs,” depicts some of the other recent Plowshares actions. It also takes necessary pains to remind us why nuclear weapons are an abomination worth risking jail time to protest. I say necessary because those of us who came to awareness after the Cold War have been taught to only worry about the weapons of mass destruction that other countries might wield—Iraq, Iran, North Korea—while allowing ourselves to regard the far more massive arsenal at home as a benign relic. On the contrary, our country’s nuclear weapons remain a clear and present threat to the survival of life on Earth. And President Trump wants drastically more of them, even while he plays games of bait-and-tweet to compel other countries into disarming.

Steve Kelly, S.J., who participated in the Kings Bay Plowshares action and others, also appears in Ms. Young’s film. “We cannot be fully human while even one nuclear weapon exists,” Father Kelly says. Several fellow Kings Bay activists appear in the film, including Catholic Workers Carmen Trotta and Patrick O’Neill. Watching the footage now, as Mr. Trotta and Mr. O’Neill mingle among Plowshares veterans, one wonders whether they had already decided they would be next.

April 4, the day they entered the Kings Bay base, was the 50th anniversary of Martin Luther King Jr.’s assassination. In their public statement, they recalled Dr. King’s linking of “the giant triplets” of racism, extreme materialism and militarism. “We repent of the sin of white supremacy that oppresses and takes the lives of people of color here in the United States and throughout the world,” the activists said.

They are speaking to us, I think—a generation whose schools have replaced nuclear-attack drills with active-shooter drills, a generation for whom drone strikes abroad are part of the normal background noise, as are police shootings of unarmed souls. They remind us that racism is as dangerous as a city-flattening bomb and that despite being out of sight, the bombs are as ever-present as micro-aggressions and mass incarceration.

The Kings Bay Plowshares Seven remain in jail after more than a month. Is their jail time worth it?

The Kings Bay Plowshares Seven remain in jail after more than a month. Is their jail time worth it? Does it do any good? Daniel Berrigan put an answer this way in his memoir:

To see nothing happening; this makes no difference: so we are told by our sternfaced tradition, our Scripture, the voice of prayer, the voices of the great dead. The end is the means: this is the message, it and the medium are one. Little difference that the end is delayed, even beyond our lifetime (if indeed we are so fortunate as to survive the immediate years ahead). Keep at it, keep at it. The skies are adamant, the ears of the powerful turn to stone. No matter: keep at it.

The postcards my family has received from the Seven, in reply to those we have sent, mostly contain the minutiae that keeping at it requires. Carmen Trotta notes that the food does not compare well to that in the jails of Honduras and Egypt and tells of being prayed over in tongues. Adds Martha Hennessy: “We are doing well but sure miss our grand kids.” It is the one from Liz McAlister that brings up the question of efficacy.

“Together,” she wrote before signing off, “we can make these weapons history.”

Nathan Schneider is a professor of media studies at the University of Colorado Boulder. He is the author of Governable Spaces: Democratic Design for Online Life and God in Proof: The Story of a Search From the Ancients to the Internet.