ATLANTA >> The mural of U.S. Rep. John Lewis, D-Ga., looms seven stories high over Auburn Avenue, the storied center of black life here during the days of segregation. Above Lewis’ blocky, instantly recognizable head is a single word: HERO.

It reflects his multiple roles in the civil rights movement as a veteran of the 1960s Freedom Rides and lunch-counter protests, and the Bloody Sunday march in 1965 over the Edmund Pettus Bridge in Selma, Alabama, a history of activism that provided the moral backdrop for last week’s sit-in on the floor of the House of Representatives in a doomed effort to prompt a vote on gun-control legislation.

The House sit-in, which ended Thursday after 25 hours and was motivated by the June 12 nightclub massacre in Orlando, Florida, returned Lewis to a familiar role as he joined hands with his Democratic colleagues who sang “We Shall Overcome” and invoked the spirit of the Rev. Dr. Martin Luther King Jr., once Lewis’ close ally in the fight to end state-sanctioned segregation in the South and elsewhere in the United States.

But the protest also raised questions that have ebbed and flowed over decades about the relevance, scope and power of the civil rights movement, when it can be invoked for issues beyond the fight for racial equality and whether it is still a living part of American politics or just a sanitized totem to be evoked by those on the left. The protest also demonstrated that the old methods, now part of a revered historical narrative of heroism and sacrifice, still have the power to provoke and offend, just as they did at the peak of the movement’s influence in the 1960s.

So, regardless of the wording on the mural in Atlanta, the reaction to Lewis and the Democratic protest from a number of conservatives was something decidedly less than hero worship.

“I’ve never seen anything so uncivilized in my life,” conservative commentator Stacey Dash, an African-American, said Thursday on Fox News.

U.S. Rep. Mark Walker, R-N.C., posted on Twitter: “Calling this a sit-in is a disgrace to Woolworth’s,” referring to a 1960 sit-in at a whites-only lunch counter at the department store in Greensboro, North Carolina, that drew attention to segregation.

Lewis, 76, an unabashed liberal who has represented his Atlanta congressional district since 1987, clearly had no such qualms. In a news conference on the Capitol steps, he promised to continue pushing for gun-control legislation, and invoked the lyrics of the folk song, based on the old standard “Gospel Plow,” that served as a soundtrack to a movement he helped lead.

“Don’t give up!” he bellowed. “Don’t give in! Keep the faith, and keep your eyes on the prize!”

For a younger generation of liberals, whose knowledge of the 1960s can come only from books, movies and museums, and their parents, it was as though the movement, trapped in the amber of the past, had been reanimated before their eyes.

“Dr. King, John Lewis and the other participants in the civil rights movement had an objective to change America for the better, and there were those who were resistant and wanted to maintain the status quo,” said U.S. Rep. Hakeem Jeffries, D-N.Y., a 45-year-old African-American lawmaker who participated in the sit-in. These days, he added, “there are those in Congress, representative of both Republican leadership and rank-and-file members, who want to maintain the status quo and do nothing in the face of mass shooting after mass shooting after mass shooting.”

Many conservatives find such analogies deeply unfair. Nearly all conservatives in public life now agree that the civil rights movement’s push to dismantle segregation was necessary and appropriate. But many of them bristle when the movement is invoked to justify liberal positions on gay rights, economic equality, health care and gun control, which they often view as cynical efforts to wrap bad ideas in sanctimony.

“The most outrageous policy proposals are invariably described as the promotion of ‘civil rights,’” conservative author Ann Coulter wrote in her 2012 book “Mugged: Racial Demagoguery from the Seventies to Obama.” “As long as liberals label something a ‘right,’ they never have to explain why it’s a good idea.”

Jim Jess, vice chairman of the Georgia Tea Party, said in an interview Friday that he saw no connection between gun control and civil rights. “In fact,” he said, “a lot of people in the African-American community are likely to want to exercise their right to bear arms, so it’s sort of disingenuous.”

Walker’s North Carolina district includes Greensboro, the site of the sit-in campaign at an F.W. Woolworth store. In an emailed statement, Walker said the protesters in 1960 “were protesting the denial of essential constitutional rights to all people. The bravery of those men, and the rights they fought for, were not represented on the House floor this week.” In his Twitter post, he said the Greensboro protesters “sat-in for rights. Dems are ‘sitting in’ to strip them away.”

The House Democratic leader, Nancy Pelosi, said her caucus had hoped to pressure Republicans to allow floor votes on a measure that would toughen background checks for gun purchases, and on one that would ban gun sales to anyone on the federal government’s terror watch lists.

A number of Republican lawmakers, as well as some civil libertarians, argue that the latter proposal violates the right to due process, because people on the watch lists have no opportunity to contest their inclusion in court.

The broader question of the civil rights movement’s proper purview dogged even King. He lost allies when he announced his opposition to the Vietnam War, and struggled, in the year before his 1968 assassination, to mount an ambitious “Poor People’s Campaign,” in which he had called for, among other things, a guaranteed annual income for the poor of all races.

Hank Klibanoff, a civil rights historian and former managing editor of The Atlanta Journal-Constitution, said he admired Lewis for injecting himself in the policy fights of the day, no matter whose feathers he ruffled. According to The Journal-Constitution, Lewis has been arrested more than 40 times, including a 2013 immigrants’ rights rally in which he and others blocked traffic in front of the Capitol.

“He finds himself, time and again, showing that he is willing to get in the way,” Klibanoff said.

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