It's literally a conspiracy theory. The theory is that the German military executed millions of people using exotic means such as masturbation machines, steam chambers and death roller coasters without the civilian population knowing. Then destroyed nearly all of the bodies. They only communicated in coded language and falsified the records of the camps so no official documentation of the murders exists. This the actual theory. The only "evidence" is eye witness testimony, nearly all of which is obviously and provably false, confessions gained under torture, and some photos of emaciated bodies who were supposedly gassed. The reason you're so violently attacked for questioning it is because it's a conspiracy theory even dumber than Q.