Bill O'Reilly, former Fox News pundit and best-selling author, thinks that US President Trump doesn't know enough about the horrors of the Holocaust and Nazism.In an opinion piece published on The Hill, O'Reilly said that this lack of historical knowledge is at the heart of what happened in the aftermath of the Charlottesville "Unite the Right" rally. "What about the alt-left that came charging at, as you say, the alt-right? Do they have any semblance of guilt?" Trump said during an August 15 news conference. "You had a group on one side that was bad and you had a group on the other side that was also very violent and nobody wants to say that but I will say it right now."For Bill O'Reilly, this response was a mistake and shows that the US president doesn't understand the full scope of Nazi horror."No other discussion can take place when Nazis are being analyzed," O'Reilly said. "Mr. Trump saw violence by some counter-protesters and pointed it out. But when a young woman is killed by an alleged Nazi sympathizer, that point must wait to be made."While there are certainly good people who want to keep the Robert E. Lee statue, the "proximity of white supremacists to the situation obscures the point," O'Reilly continued.However, he did not think Trump's mistake was malicious, nor should he be branded as a Nazi sympathizer, saying that "truth is always the first casualty of hysteria."And Trump is far from the only history-challenged person according to O'Reilly."I can tell you with certainty that most people on this planet have no clue as to how German Nazis went about their lethal business. And that includes President Trump and many other politicians both present and past," O'Reilly wrote.He lamented that the Second World War was hardly taught in US schools and that Hitler had become a "caricature of evil, a distant monster" when he should be taught as something real and vivid."Mass murder was carried out by ordinary Germans while the vast majority of that population looked away out of self-interest and fear," he stated. "These people weren't from another planet.""The crimes of Hitler's regime and the population that allowed it were so terrible that words cannot come close to description. Yet words are all we have."If we were taught more in-depth about the horrors of Nazism and the crimes of the Third Reich, O'Reilly concluded, Americans would have been united against hate after Charlottesville, not divided by politics.