The horrific massacre of at least 10 people in a supermarket in Buffalo should be a wake-up call to the nation: Racism is a poison in our nation’s bloodstream. People were doing their shopping and were mowed down by a white supremacist who drove for hours to kill Black people. Proud of what he was doing, he live-streamed his monstrous actions. Only 18 years old, but his heart was already twisted and warped by racism. The early reports say he avidly consumed racist social media. He absorbed the Great Replacement Theory, the fear that white people like him were losing control. So he murdered innocent people in a supermarket.

There was a time, however briefly, when white supremacists hid under a rock and kept their loathsome views to themselves. But then Trump told them that “political correctness” was dead. It was okay for them to spout their venom, and he encouraged them.

It didn’t start with Trump; racism has been part of our nation’s history for hundreds of years. Our history is full of lynchings, massacres, systemic cruelty to a people whose only “crime” was their skin color.

And yet we dared to hope that racism was a thing of the past. In the 1960s, with elected officials passing laws to punish it, and the courts upholding those laws, we imagined we had driven it out of our social fabric and delegitimized it. We did not.

Racism is not in the past. It never went away. It is out in the open, supported by white supremacists like Tucker Carlson, by FOX News, and by racist social media. Racism is legitimated by the states that passed laws banning “critical race theory” (that is, discussions of racism) from their schools and universities. It is openly endorsed by states banning the teaching of “The 1619 Project,” which explores in painful detail the history of racism.

How can we begin to understand what happened Sunday in Buffalo?

Read “The 1619 Project.” Engage wholeheartedly in critical race theory. Read and discuss the systemic racism that encouraged an 18-year-old man to strap on battle gear and go in search of innocent black people to kill. Vote against the legislators who have tried to suppress knowledge of and teaching about racism.

Search your conscience. Ask why so many states are banning books about racism, preventing teachers from talking about it, preventing students from learning about it, and criminalizing the study of its roots.

This mayhem will not stop until we white people look honestly at our history and into our mirrors.