A'isha
Miss Schoolteacher
This is the problem. If there is no consensus definition of the Holocaust, then the word doesn't have any real meaning. If there's no definition of the Holocaust then how can we define what it is to be a victim of the Holocaust?
The Nazis weren't so kind as to leave us a specific definition and headcount of everyone they systematically targeted and murdered. That information has to be gleaned by historians from a wide variety of sources, and different historiographic methodologies (often combined with new information that comes to light during historical investigations) result in different results sometimes. That's how history works.
Again, Gerlach discusses all this in the book I cited above.
According to Pew, 73% of Jews say that remembering the Holocaust is an essential part of what it means to be Jewish to them. Only 19% consider observing Jewish law to be essential part of what it means to be Jewish. 68% of Jews say that a person doesn't need to believe in God to be Jewish. Clearly, the Holocaust is important to the Jewish community. If somebody insists that almost half the victims of the Holocaust were not Jewish, wouldn't that same person have to agree that it's a little self-centered for Jews to care so much about it?
No, since while the Nazis systematically persecuted and murdered a whole lot of different groups, they (from Hitler on down) had a particular focus on Jews, and Jews formed the primary victims of both Nazi rhetoric and their campaign of genocide.
If you add up all the other groups who were victims of the Nazi program systematic murder, it can almost equal (or exceed) the number of Jewish victims. But you still have to add up all the other groups together to do so. The millions of Jewish victims were all part of a single group.
And if something horrible happened to millions of people and only some of those people were Jews, why would a Jewish person or anybody at all think that it's anti-Semitic to deny it?
Because of the above.
I don't believe in diluting the word into meaninglessness. Yad Vashem uses Holocaust and Shoah interchangeably.
"Shoah" was a word chosen because the word "holocaust" has unpleasant religious connotations. However, "holocaust" is still how it's most commonly known, so that's the word that's most often used, even by people who prefer the term "shoah".