You can't help someone who doesn't want help, especially a narcissist, and racist narcissists are the absolute worst because instead of terrorizing one target, they seek to destroy everyone who isn't white like them.
Do yourself a favor and tell them to go fuck themselves. Redirect your energy into creating practical change. You don't see white supremacists and neo-Nazis try to change your mind. They only seek to destroy. They direct their energy into infiltrating and imposing their influence in every corner of government and profession. They gaslight and oppress the vulnerable and malleable into believing words more than actions. They don't have to change your mind. They just need to waste your time by convincing you that the house is not on fire until there is nothing left to save.
Anyone, who's dealt with narcissists in their lives, knows that narcissism is a mental illness that can be clinically diagnosed. White supremacists are racist narcissists. They will tell you that they come in peace, then stab you in the back. They will take a vow to protect you and then calmly kneel on your neck. Psychologists tell victims of narcissists that the only way to deal with them is to walk away because they're that destructive. And, to call the cops if the narcissist is violent. But, wait, our police are racist too. The house is on fire, people!
A regular racist most likely still has compassion and is just brainwashed. Set an example and let them rise to you. Do not stoop to parent them. A white supremacist is a narcissistic racist who lacks empathy and seeks to destroy and/or gaslight their victims. Do not engage. People with tiny hearts and narrow minds are extremely dangerous.We can't be distracted by their racist rhetoric and lies any longer.
If it quacks like a duck and looks like a duck, it's a fucking duck. Don't give them the time of day, use your energy to fight the flames. Whether they're a racist or white supremacist, you're not hurting them by ignoring them. They'll happily walk into the house later acting like they didn't try to burn it down.