Not only will the deniers focus only on the gas chambers, but they only deal with the Auschwitz camp. This was both a slave labor camp and an extermination camp. There were many other camps as well, but they were small points on the map to which trains transported thousands to their death. Holocaust deniers reject all evidence and claim that all documents and photographs are forgeries. Even survivor eyewitnesses are said to be delusional.
Most historians revise history in some form or fashion.
A second look at the past is taken, and it is revised in the light of new evidence and new perspectives. Historians will ask questions, such as what happened, how did it happen, and why did it happen. They will not deny the events ever happened. In contrast with this, Holocaust deniers flatly say that it never existed, and it is a mere invention of the imagination of the Jews. In other words, the criminals are innocent, and the innocent are criminals.