Editor's Note: (Jonathan Greenblatt is CEO and national director of the Anti-Defamation League. Before joining the organization, he served in the White House as special assistant to President Obama and director of the Office of Social Innovation and Civic Participation. The opinions expressed in this commentary are his.)
(CNN) Donald Trump claimed he is not familiar with David Duke.
It is hard to believe, but we will choose to take him at his word and use this opportunity to explain in detail to him -- and indeed all candidates -- who David Duke really is.
It seems that Trump did have a change of heart after a public outcry over his comments about not knowing who Duke was. Trump later tweeted his disavowal of Duke. Still, we believe Trump and the public need to be aware of the kind of hate and extremism that Duke espouses.
David Duke is a racist and anti-Semite and a former Imperial Wizard of the Knights of the Ku Klux Klan. Duke has been on the American radar screen nationally as a one-time Louisiana legislator, as a failed candidate for the governorship of Louisiana, the U.S. Senate, the U.S. House of Representatives and the presidency -- and through his career as a spokesman for white supremacy. His message is racist, anti-Semitic and anti-American to its very core.
Most recently, Duke has been among a number of white supremacist individuals and groups to have endorsed Trump's candidate for presidency. What's worse, white supremacists are voicing support for Trump in articles and blogs, are retweeting him on social media and congratulating themselves for finding a new way to get attention to their hateful message.
Outwardly, Duke has cultivated the image as an attractive, articulate and media savvy political activist. But on closer examination, the real David Duke emerges: a former Ku Klux Klan leader. The positions he has articulated are no different from those of other, less savvy racists and anti-Semites who still wear robes and speak the crude language of hate and racial violence.
He has asserted that as a boy in Louisiana, he "learned" that animals have different genetic codes, which dictate their behavior and disposition, and it stands to reason that, just as breeds of animals differ, human races must also. Through a slow process of uncovering "painful truths," Duke has claimed to reach the bigoted conclusions that black people really are inferior, homosexuality is unnatural and that it is wrong for women to aspire to the same types of careers aspired to by men.
In Duke's hateful view, worst of all are the Jews whom he wrongly blames for most of the major destructive political movements the world has known and who he falsely says have systematically focused the world's attention on their suffering through gross exaggeration of the Holocaust and control of the institutions that disseminate information.
More than 40 years ago, Duke's views inspired him to found the Louisiana-based Knights of the Ku Klux Klan, of which he appointed himself Grand Wizard. In so doing, he was drawing on a tradition of KKK racism that dates back to the aftermath of the Civil War.
The Klan itself is synonymous with evil. In its early days, its members, dressed in infamous white robes and hoods, not only terrorized former slaves but also harassed, intimidated and even lynched Northern teachers, judges, politicians and "carpetbaggers" of all ilk.
The KKK has gone through several incarnations and revivals since, but its underlying racism and anti-Semitism have been a consistent theme. David Duke understood that robes and hoods were no longer viable and believed his responsibility was to repackage, intellectualize and dress up its ideas. But those ideas, at their core, still represent the crudest and most destructive form of hatred of other races.
In his autobiography, published in 1998, Duke issued a clarion call to "Aryans" to join the battle, urging the same strategies he used in his attempt to camouflage the Klan as a "respectable," nonviolent political organization.
"Every Aryan must come to realize," he said, "that truly hateful rhetoric or terrorism only fulfills the false, Jewish-created, media image of what we are and what we stand for."
He called for solidarity among white supremacists and stressed the importance of education, nonviolence, organization and familiarity with the Internet.
As someone who has spent his entire career attempting to obfuscate, hide and dress up ideas that represent the crudest and most destructive form" of prejudice and bigotry, Duke is -- regardless of whether he is wearing a robe and hood or a suite and tie -- an unabashed racist and anti-Semitic hatemonger.
In today's politics, there is a place for reasoned debate about issues of race in America, affirmative action, profiling and many other issues about which reasonable people disagree. But white supremacists, who believe in the superiority of one race over others, have no place at the table.
Advocacy of extremism and hatred is not reasoned debate, and it should be rejected outright across the political spectrum.
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