We live in a post-civil-rights era—a time in United States history when overt racial discrimination is illegal yet racial violence and inequality remain unrelenting. The paradox stems from a liberal civil-rights agenda that has failed to root out deep, systemic racial injustices while championing superficial racial equality under law. For decades that focus has stymied movements for transformative change.  

But when, exactly, did the post-civil-rights era begin? Arguably, it was 50 years ago today, when in a speech at Harlem’s Riverside Church, Martin Luther King Jr. definitively broke ranks with the liberals he once considered allies.

“Beyond Vietnam: A Time to Break Silence” wasn’t any kind of obligatory antiwar statement. (Actually, he also spoke out against the war two months earlier, at an event in Los Angeles sponsored by this magazine.) Rather, the Riverside speech was his declaration of no confidence in the nation’s leading liberals, particularly the Johnson administration. On this spring evening in front of packed pews, exactly one year before his assassination, King explained how the US leaders who had championed civil-rights protections were never truly invested in full equality for African Americans. The clearest evidence of this was their murderous foray into Vietnam. King correctly understood that so long as liberals sent armies abroad to perpetrate racial violence they could never plausibly achieve true racial equality at home. King’s speech was a summons to transcend a civil-rights program that lacked what he termed “true values,” to soar above a hollow civil-rights agenda that cared only for disassociating itself from the crude optics of the Deep South. King believed that only a “radical revolution of values” could conquer the “giant triplets of racism, extreme materialism, and militarism” that were at the heart of American apartheid.

This didn’t go down well with King’s former allies. Most liberals frowned on his antiwar statements, and the media excoriated him. President Lyndon Johnson disinvited King to the White House, severing his ties with the civil-rights icon. This break has defined the past fifty years of US liberalism.

King anticipated the reaction, and he wanted others to know he knew the risks. At the beginning of his speech, King reported that many had cautioned him against coming out against the war: “ ‘Peace and civil rights don’t mix,’ they say. ‘Aren’t you hurting the cause of your people?’ they ask.” In response to his critics, King offered a simple, chilling observation: “They do not know the world in which they live.”

It was a world in which the “hopes [and] new beginnings” of federal antipoverty programs were quickly exchanged for the build-up of US forces in Vietnam. Such programs were left “broken and eviscerated,” abandoned like “some idle political plaything” by “a society gone mad on war.”

King went on to take stock of the devastating human and environmental destruction the United States had wrought on a small country that began its fight pursuing the cause of self-determination against French colonialism. After the Vietnamese revolution ousted the French, it sought a peaceful resolution to national reunification—only to be thwarted by US intervention. “Our government felt then that the Vietnamese people were not ready for independence,” King observed, “and we again fell victim to the deadly Western arrogance that has poisoned the international atmosphere for so long.” Thus King put to rest any questions about his anti-imperialist leanings.

The Riverside speech wasn’t idle commentary for the foreign-policy crowd, or a gambit directed at elected officials. Both the audience and the stakes were far larger: King was talking about “America’s soul.” For “if America’s soul becomes totally poisoned,” King warned, “part of the autopsy must read ‘Vietnam.’ ” The nation’s capacity for violence in Vietnam was a measure of its capacity for violence at home. One could not expect a nation that behaved with such depravity abroad to take seriously the work of eliminating poverty, joblessness, and environmental racism in its own ghettos. “When machines and computers, profit motives and property rights, are considered more important than people,” as demonstrated by Johnson’s war in Vietnam, then such values would no doubt guide the liberals’ treatment of the black community at home, King reasoned. He was right.

The very liberals who supported and signed civil-rights legislation while waging war in Vietnam would wind up in the years ahead being the chief promulgators of new laws that criminalized the daily lives of the urban poor and authorized the militarization of municipal police forces. The 1968 Safe Streets Act, signed by Johnson, poured hundreds of millions of dollars into building up law enforcement and the criminal-justice apparatus—astronomically more than was ever spent on the same president’s antipoverty programs. This legislation would lead to a slew of other law-and-order policies that together helped lead us into the age of mass incarceration.

Fifty years ago today, King saw the nightmare to come: “A nation that continues year after year to spend more money on military defense than on programs of social uplift is approaching spiritual death.” He implored us to avert this fate by first ending the war in Vietnam, not as a solidarity side-project but as a necessary step toward achieving our own liberation. Only after the war’s end could we earnestly begin a revolution of values that, going beyond civil rights, would tackle the profound economic inequalities that structured the nation.

The Democratic Party roundly rejected King’s plea. For the past 50 years it has engaged in new theaters of war abroad while building up massive, unconscionable wars on crime and on drugs—against the poor—at home. Through it all, the gap between poverty and wealth has grown wider, just as King predicted it would. The Democratic Party now faces an existential crisis. It would be too little and far too late for it to admit that King was right all along, but it would be an important step toward finally abandoning the party’s tradition of military liberalism. If it cannot even do that, the Democratic Party must be abandoned once and for all. The speech at Riverside Church serves as a timeless call to action, a reminder of what King called, in that same speech, “the fierce urgency of now.” Indeed, 50 year later, his words remind us that the post-civil-rights era not be the end of the story. It can also be an opportunity to build deeper and more lasting movements for racial justice.