The fact that winners write history is true and has many effects. Consider how Germany has reflected on the Nazi era and reacted very much against it. Japan's leaders were not suppressed as hard, and Japan's version of the truth is more iffy. On the other hand, when someone
really wins they need not be ashamed at all. The Jewish conquests in the early crazy Bible and also the Mongol narratives are very plain and reflect no shame whatsoever about mass killings. That said I think Holocaust disbelief is more about the fact that 6+ million dead is incredible and you would never believe it if your culture did not already totally accept it (a result of it having happened).
Rather than focus just on the Holocaust though, there seems to be consensus among white anti-Semites that the "Jews" are really Khazar Turks and the
real Jews are white people. The "Jews" have suppressed the truth by secretly taking over the Vatican, the media, and all the "democratic" governments. The "Holocaust" is simply another reflection of their lies. This view is alarmingly compatible with mainstream evangelical Protestantism. On the other hand, people who take historical revision really far, as in the
Fomenko Chronology, are basically the lolcows among anti-Semites. They say that the Exodus and the Illiad happened at the same time in Italy 500 years ago, when Moses became the Pope. Having taken over openly, the Jews then suppressed anyone who told the truth until everyone forgot what really happened.
About nationalism, I fear that left and liberal leaning people (I say this as a Democrat voter) have turned it into a bad word. Nationalism generically just means opposing foreign rule, and usually implies opposing aristocratic and traditional forms in favor of some republican/democratic form, even if only rule by referendum.
Ultranationalism though (ultra = beyond) is what would lead Hitler for example to declare that the Dutch and Austrians are really Germans (true) and therefore are naturally part of Germany (only true if someone makes it so). And
ethnic nationalism is what gives the Beijing government the right to treat non-Chinese like garbage, for example.
