Holocaust deniers...anti-semitic?

For most of my life I've watched documentaries about the Holocaust and have over the years read articles that directly or indirectly broached the subject. I still have my copy of The Life and Death of Adolf Hitler, Robert Payne, London: Corgi, 1973 the book I read whilst I was pregnant with my son in 1977. I can't really remember why this book appealed to me except that I wanted to understand why the Holocaust occurred. I thought reading about Hitler's life would give me some insight.  I still have the little pink stickers that mark the pages where I've underlined significant information. The first was about the book that was highly influential for Hitler, and I quote: 'The book was Schopenhauer's The World as Will and Idea (Die Welt als Wille und Vorstellung, 1819), which celebrates the primacy of the will, seeing it in romantic isolation, detached and inviolable' (156).  The second is 'Hitler's way of dealing with a man who could out-argue him was to knock him to the floor' (215) and lastly, I marked the section about how exterminations were carried out at Auschwitz. For me, as for many others there is no doubt at all that the Holocaust occurred and a general search with the word Holocaust in the Melbourne University Library results in 137065 entries, attesting to the fact that much scholarly research has been undertaken on the subject.  One of my son's main concerns was how to decipher fact from fiction, particularly when undertaking research on the Internet. I've suggested that articles that do not cite their sources are not (at least for me) read-worthy. So, this post is primarily for my son who is asking whether the Holocaust really happened amidst overwhelming historical evidence and a growing number of Holocaust revisionists (most deniers) who are considered by many to be  displaying antisemitism. As the Anti-Defamation League has said:

Holocaust denial is a contemporary form of the classic anti-Semitic doctrine of the evil, manipulative and threatening world Jewish conspiracy. It was this doctrine that was instrumental in laying the groundwork for the Holocaust. What is on the surface a denial of the reality of genocide is, at its core, an appeal to genocidal hatred.

I direct him now to Michael Shermer (Author) Alex Grobman (Author), Arthur Hertzberg (Foreword) who wrote the book: Denying History: Who Says the Holocaust Never Happened and Why Do They Say It? published by University of California Press in 2009.
He asked last night about Hitler's anti-semetism and I directed him to Mein Kamf (My Struggle). Hitler's views about the Jews in Germany are described in Volume 1, Chapter 2: Years of Study and Suffering in Vienna and he outlines his ideas about the influence of the Jews and his notion of racial purity in Chapter XI: Nation and Race.
Revisionists (and conspiracy theorists) deny that Germany had any policies  in place to eradicate Jews and yet evidence of Hitler's desire to annihilate Jewery is displayed in a number of instances. Here is a link to Hitler's Speech to the Reichstag in 1939. There is no doubt in my mind that Hitler engineered a total and systematic plan to exterminate Jews in Europe (the Final Solution). There is a document which gives detailed statistics of the killings in the extermination camps - Belzec, Sobibor, and Treblinka, and the Concentration Camp Lublm-Majdanek (fortnightly report - December 1942 - total 1,274, 166!
In regards to the use of lime, which dissolves a corpse ~ initially in Operation Reinhard  the bodies were placed in deep pits and covered with lime, however this method was rejected in favor of  cremation. Payne says that 'After the bodies were cremated, prisoners were given small hammers to break up the bones, and then the ashes and small bones were thrown into the nearby Weichsel River' (607-608).
I  hope that this information helps him work through some of the issues, but really, my question is why has denial of the Holocaust happened at this moment time and what might in mean in terms of current world politics?