You can stop worrying about the Zombie Apocalypse. America now has a more pressing domestic crisis to address. From Charlottesville, Va., to the White House and beyond, the ghosts of racial hatred and white supremacist ideology are loose upon the land. The bones of Bull Connor, Lester Maddox, George Lincoln Rockwell, Nathan Bedford Forrest and other bully boys are still safely underground. But the spirit that animated their racist vitriol haunts Donald Trump's America.Six months into the new administration, the movement to "Make America Great Again" appears to be little more than a re-mastering of Jim Crow culture's greatest hits: Negrophobia, anti-Semitism, xenophobia and Ku Kluxism. Perhaps the politics of Trumpism will eventually morph into something more positive, but at present the prospects for legitimate reform do not look very promising.Hate-filled expressions of exclusionist ideology are suddenly all around us — sometimes whispered in hushed tones but more often shouted by angry and desperate voices. Cries of defiance and intolerance generally associated with European totalitarian Nazis and brown-shirt fascists can now be heard on the streets of mainstream America, often as calls for white nationalism and ethnic cleansing. In recent days, statues honoring Confederate soldiers and politicians — 700 of which dot the Southern landscape — have become rallying points for the mobilization of white partisans, not only of the Lost Cause, but also of Neo-Nazism and other forms of "alt-right" extremism. Defended as historical icons by regional heritage groups such as the Sons of Confederate Veterans and the Daughters of the Confederacy, these statues were, with few exceptions, constructed in the early 20th century, long after the close of the Civil War. Artifacts of the Jim Crow South — where disfranchisement, discrimination, and cradle-to-grave segregation ruled until the civil rights revolution of the 1960s — serve as important and often intimidating symbols of white power and privilege, especially when their stony visages preside over parks or on courthouse lawns. Sending a clear message to African Americans, white dissenters and meddling Yankees, they assert that — despite the continuing struggle to democratize the South — Dixie remains a white man's domain. To the many Americans calling for the removal of these statues, this neo-Confederate iconography pays unwarranted tribute to the evils of secession, treason, slavery and racism; and as such it represents an offensive affront to American democracy. To the alt-right, however, these monuments to sectional resistance reflect the grievances of economically dispossessed and culturally disrespected white men, those desperate to express their seething contempt for a national political establishment addicted to cosmopolitan smugness, multiculturalism and globalism.This alchemy of hate and resentment took center stage when Richard Spencer organized a massive "Unite the Right" rally in Charlottesville, the home of Thomas Jefferson's hallowed university. The stated rationale for the rally was the protection of a statue of Gen. Robert E. Lee scheduled for removal.This attempt to bring force and intimidation to the campus grounds and the area in and around Emancipation Park (formerly Robert E. Lee Park) had all the earmarks of a paramilitary operation. It was quite simply an invasion of a public space by a private army, a calculated outrage designed to provoke a counter-protest of progressive-minded citizens. Most of the counter-protesters, including a number of clergymen, pacifists, and Black Lives Matter activists, were peaceful activists committed to nonviolence. But there were exceptions within their ranks, and the absence of complete nonviolent discipline all but ensured the violent confrontation the alt-right organizers craved. The white nationalists and neo-Nazis came to Charlottesville for blood, and they did not go away disappointed. Before the melee was over, the death of 32-year-old Heather Heyer and the serious injuries inflicted on dozens of other counter-protesters testified to the alt-right's willingness to embrace violence and even civil war.Some counter-protesters, including those representing the militant antifa (anti-fascist) movement, engaged in active resistance, an action that only served to fuel the fury of the assault. But most drew back in horror at the sight of hundreds of bigoted white thugs marching in formation, many carrying torches or signs festooned with swastikas.Some wore military-style helmets and carried shields, while others wielded long guns and assault rifles. And virtually all chanted traditional Nazi slogans — "blood and soil," and "Jews will not replace us," daring anyone to challenge their control of the streets. The brazen aggression of this thuggish clamor has led some to characterize it as unprecedented in the American experience. But this comforting, salvific interpretation flies in the face of our nation's long history of racial oppression and civil disorder. While America's past includes many redemptive themes worthy of celebration, white supremacist violence is undeniably part of our political DNA. Indeed, we do not have to go back very far to find episodes foreshadowing recent events. For Americans old enough to remember the massive resistance campaigns of the 1950s and 1960s, the mayhem in Charlottesville evokes frightening memories: the mutilated body of 14-year-old Emmett Till lying in an open casket in Chicago following his 1955 murder by white supremacists in Money, Miss.; the hard-core segregationists screaming at black children trying to enter Little Rock's Central High School in 1957; the anti-Freedom Rider riots in Anniston, Birmingham and Montgomery in 1961; the shameful "Battle of Oxford" prompted by James Meredith's attempt to desegregate Ole Miss in 1962; the 1963 murder of four little girls attending Sunday school at Birmingham's 16th Street Baptist Church; and the "Bloody Sunday" assault on John Lewis and other voting rights activists trying to march across Selma's Edmund Pettus Bridge two years later. The list of white supremacist atrocities could go on and on, but the brief sampling above should be sufficient to remind us that Charlottesville is not an anomaly.Many of us hoped we had gotten beyond all this, that the civil rights struggle had brought us within reach of the "beloved community" envisioned by Dr. Martin Luther King Jr. But I fear we were wrong, not in our perception of the real progress that has been achieved but rather in the belief we are no longer vulnerable to the machinations of unprincipled bigots and rank demagogues.A nation dedicated to the ideals of democracy and freedom is now at risk, needlessly threatened by Donald Trump's refusal to identify and condemn the perpetrators of the carnage in Charlottesville, by his failure to exercise the moral authority of his office on behalf of common decency, by his attachment to mythic fantasies at odds with historical reality, and by his expanding role as provocateur in chief.No president in living memory has acted so irresponsibly in the face of domestic terrorism, so in at least one important sense, the crisis at hand is different from the challenges of the past. With the presidency morally and ethically compromised, our standing in the world is now in jeopardy. For the sake of the democratic republic we hold dear, it is time for all Americans of good will to stand up for justice and equality.Raymond Arsenault is the John Hope Franklin Professor of Southern History at the University of South Florida St. Petersburg. He wrote this exclusively for the Tampa Bay Times.