1. The post WW2 books written by the wartime leaders Churchill, Eisenhower, and De Gaulle never mentioned any gas being used or any planned, systematic extermination of anyone
.2. In Eli Weisel's book titled 'Night' he doesn't mention gas being used. And when the choice came that he would retreat with the Germans, or stay and be under the Soviet umbrella he chose to retreat with the Germans.
3. If millions were murdered then there would have been tons of human remains buried somewhere, and it would be way too much to hide for very long. No tons of human remains were ever found. And if they would have been cremated then there would have been tons of ashes and no ashes were ever found.
4. Red Cross visited Auschwitz, and they found nothing wrong.
5. Auschwitz was a place where synthetic rubber was being produced, and U.S. intelligence was focused on Auschwitz for that reason. No U.S. intelligence reports ever gave any indication of gassing or mass extermination.
6. In 1939 fact book World Almanac calculated that there was a world Jewish population of 15,748,091. In 1947 they calculated that the world Jewish Population was 15,690,000.
7. Torture used at Nuremberg Trials: The greatest argument in favour of the Holocaust is that "the Germans admitted it." The best response is to point out that the Nazis who "admitted" the Holocaust at the war crimes trials were tortured by their (mostly Jewish) interrogators, usually by having their testicles crushed; you can get almost anyone to confess to anything with the correct torture techniques.