As a black, queer woman, Khan-Cullors is the kind of activist conservative politicians get panicky about, though they ostensibly share with her an overlapping area of concern. While they extol the importance of family and community (in word if not always in policy), Khan-Cullors sees the cultivation of family and community as central to what she does, too.

She has publicly blasted Democrats for having “milked the black vote while creating policies that completely decimate black communities,” referring to the crime bill that President Bill Clinton signed into law. Her father, whom she describes as a gentle man struggling with addiction, was in and out of prison on drug charges until he died of a heart attack in a homeless shelter. Her brother Monte, who has schizoaffective disorder, went to prison for yelling at a woman after a fender bender. For Khan-Cullors and her neighbors, “the mass incarceration of first our fathers and later our mothers made our lives entirely unsafe,” she writes. “There were almost no adults who were there, present to love and nurture and defend and protect us.”

Image Asha Bandele, co-author of “When They Call You a Terrorist.” Credit... Michael Hnatov Photography

A word that Khan-Cullors keeps repeating in her book is “love”: “I want a family, a core, a loving and stable center to return to, to awaken to.” When a petition was circulated in the summer of 2016 to declare Black Lives Matter a terrorist group, gaining enough signatures to reach the White House, she felt crushed. But then as Jeanne Theoharis shows in “A More Beautiful and Terrible History,” civil rights activists half a century ago faced a similarly hostile reception. The difference now is that the example of yesterday’s activists is used against Black Lives Matter today.

Even many of those “who claim sympathy with BLM’s purpose have used the civil rights movement to decry their tactics,” Theoharis writes in her elegant introduction, her rage kept at a controlled simmer. Theoharis, a historian and the author of “The Rebellious Life of Mrs. Rosa Parks,” is particularly attuned to how the legacies of Parks and Martin Luther King Jr. have been co-opted into a narrative of uplift, with civil rights history sanitized for public consumption.

Image Jeanne Theoharis, author of “A More Beautiful and Terrible History.” Credit... John Riscoli

At a time when conservative calls to stop “politicizing” Martin Luther King Day have become a yearly tradition, Theoharis’s book is a bracing corrective to a national mythology that renders figures like King “meek and dreamy, not angry, intrepid and relentless.” As it happens, getting King’s birthday declared a national holiday was a 15-year ordeal. King was truly unpopular at the end of his life; a 1966 Gallup poll determined that only 33 percent of Americans had a favorable opinion of him. (The figure in 2011 was 94 percent.) King was surveilled by the F.B.I. and went to jail 30 times. Like many other civil rights activists, he was called a Communist — a label whose loose rhetorical function is echoed in the word “terrorist” today. He was also reviled for having the temerity to criticize the “white moderate” who “preferred order to justice.”