Were it not for the setting, the murder of one person by a possibly deranged gunman might not register the concern that it should. But where this shooting took place changes everything.

A man calmly walked into the U.S. Holocaust Memorial Museum in Washington on Wednesday, pulled out a rifle, and managed to fatally shoot security guard Stephen T. Johns before he was subdued.

That a place dedicated to remembering the millions of Jews murdered during World War II would itself become the scene of a homicide is heartbreaking. The alleged gunman, James V. von Brunn, 88, was shot by other guards, and listed in critical condition Thursday.

Von Brunn has a long history of anti-Semitism and racism. But the museum shooting shouldn't be written off as the result of one man's hatred. The vile material von Brunn spewed on a personal Web site is repeated often on the Internet.

The rage is aimed at Jews, blacks, and immigrants, especially Hispanics. The election of the first African American president was like lighting the fuse to a string of firecrackers. Who knows when the next one will go off?

"The president of the United States is really just a puppet in the arms of ZOG [Zionist Occupied Government]," said a racist Web site post after Barack Obama's election.

Little can be done about such venom, other than to watch those who produce it, hoping to detect a crime. Von Brunn's site was among those monitored by the Anti-Defamation League and Southern Poverty Law Center, but they couldn't predict his actions.

While they watch, the rest of us must guard against the encroachment of hateful language into what is supposed to be civil discourse.

Some of the fiercest anti-immigrant rhetoric of politicians and TV and radio personalities has made the haters bolder. They take it as a call to arms when a Latina Supreme Court nominee is called a "racist." For them, the recession has been an excuse to blame the Jews for financial problems.

In such an environment, it's not hard to produce a gunman who would attack the Holocaust Museum, or shoot soldiers at a recruiting center, or kill a doctor who performed abortions. To change the environment, people must change the language they use.