At first this question really surprised and shocked me. How could anyone seriously believe that Adolf Hitler didn’t order the death of six million Jews? Then I learned that a lot of people think the Holocaust is, in words that Donald Trump might use, although not about this subject, “fake news”. The Holocaust is not fake news. The Holocaust is not a tall tale. Neither is the Holocaust a myth or a conspiracy theory. How could anyone ignore the evidence of the Holocaust provided during the Nuremberg trial? Much of the proof the Holocaust existed was provided by the Nazis themselves. They documented their crimes by photographers and camera crews.
They were sickeningly proud of what they had done. The evidence consisted of documents, photographs, movies, and testimony from survivors and perpetrators. Choose whatever synonym you like: incontrovertible, unquestionable, indisputable, irrefutable – they all describe the evidence that proves the Holocaust did happen for real.