Charlottesville will be remembered as an ugly scar on American life.

“Racism is real,” Republican Sen. Tim Scott of South Carolina put it bluntly after a white supremacist terrorist drove his car into a crowd of peaceful demonstrators. “It is alive. It is here.”

A month later, it’s still here.

Evil isn’t defeated by temporarily changing our profile picture or tweeting 140 characters of hollow solidarity under #Charlottesville. It requires a sustained and disciplined effort to confront racism in our daily lives — when we see it expressed among our friends or neighbors — and especially when it rears its ugliness in any political capacity.

“Racism and hatred have no place in the conservative movement. Full stop,” writes Townhall columnist Jason Pye.

The uncomfortable reality is that, at one time or another, both major political parties have provided aid and comfort to national socialists and white supremacists. At its peak in the 1920s, the Ku Klux Klan’s 4 million members included prominent Southern Democratic judges and elected officials at every level of government. Perhaps most infamously, the late Democratic Sen. Robert Byrd of West Virginia founded a KKK chapter on his way to achieving the Klan’s rank of “Exalted Cyclops.”

The roles have been reversed today, as “white power” extremists rally under the “Unite the Right” banner. This ideological evolution is difficult to explain if you make the mistake of considering it to be a legitimate political movement.

“The angry white boys do not have a serious political agenda,” National Review’s Kevin D. Williamson explains. “Their agenda is their anger, an anger that is difficult to understand.”

As further proof of this anger-driven agenda, look no further than the fascinating evolution of one agent provocateur: Jason Kessler. The self-proclaimed “pro-white” activist found a home in white supremacy only after serving as a Wall Street Occupier and backing President Obama, according to the left-wing Southern Poverty Law Center.

Conservatives and libertarians must be alert to what happened in Charlottesville. Ignoring the alt-right will leave a deep and permanent scar on the conservative movement. We can’t offer moral equivocations or excuses, either.

“They are the wolves in sheep clothing looking to draw more and more people into their pack, while ripping away at the foundation of freedom and liberty at the same time,” warns Hot Air’s Taylor Millard.

There’s space for nearly everyone in the Republican Party. Our movement is united by freedom for the individual from government oppression. You can be a dreadlocked homeless activist, or a buttoned-up college Republican. However, you can’t be a white supremacist or an alt-right fascist.

We’ve been here once before. The founder of modern conservativism, William F. Buckley Jr., who started National Review in the 1950s, exposed anti-Semitism on the right — and excised it entirely. This old story must be replayed to face the new threat.

Republican organizations, large and small, must actively identify white supremacists, Nazis, Ku Klux Klan members and any other alt-right extremists within our ranks, and forcibly exorcise them from the conservative movement. Don’t expect this to happen overnight.

“Anyone that expects an epiphany or a transformation to happen overnight because somebody walks in a room, I think, you don’t understand human nature,” said Mr. Scott, the first African American senator to win election in the South since Reconstruction.

The domestic terrorist attack in Charlottesville is quickly fading from the headlines, but the real work to stamp out its “white power” origins is only just beginning.

Alt-right, white supremacist followers should never be tolerated by conservatives.

Shawn Steel, a former California Republican Party chair, is California’s committeeman for the Republican National Committee.