Holocaust denial has its history itself, at least in germany.
Starting right after WW2 there was not much room to deny anything what obviously has happened. There were not too much jews left in the camps and every german noticed in the war jews just were "transported for labour" in the east - now they knew what that meant.
After all there were a lot of germans who had their assumptions. My Grandmother worked 1943 at a station and watched the trains full of jews coming from France and Netherlands. She was forbidden to give something to eat or water to the people in the trains ("Don´t give them anything, they will kill each other for just a piece of bread").
Once my Grandmother asked the engine-driver what would happen to all these people because it didn´t made sense to her sending children and old people to work in the east.
The driver told her "They all will be gased!" and my granmother never spoke about this until 2002, short before she died. Her husband helped jewish neighbours years before to get out of the country to the Netherlands. All of them but one was killed. It is quite possible, that some of that family were in one of these trains my grandma watched. I think there are a lot of germans who could tell you a similar story.
Many germans knew, more could know but decided not to look closer.
When the war ended there were confessions of the holocaust by people like Höss (commander in Auschwitz), Ohlendorf or Bach-Zelewski (commanders of "Einsatzgruppen") and Hitler himself in his political Testament.
There was the "wansee-protocol", the goebbels-diarys and many documents found later.
Even the raging antisemite Julius Streicher had no doubt in the Nurenberg Trial that the Holocaust had happened. Of course he denied knowledge of it (and that might be true) but he did not doubt it.
There were some discussions about numbers, but not that much. It was clear to everyone at that time, that the crime would be not less gruesome counting its victims 4 or 6 millions.
Maybe some germans didn´t believe (or didn´t want to believe) every detail, but all in all they knew it was true.
The first books, denying the holocaust were written by a Scotsman Ratcliffe and a french antisemite Bardeche afak.
Members of the SS and others tried not to deny the holocaust but to explain it. Hitler made his prophecy to the "weltjudentum" what would happen if "it" would start a war - extermination.
There was a motive of revenge, they tried to compare the shoa with the bombings of civilians in germany and so on.
Eichmann, while in Argentinia, did his interview with Sassen just to explain what he did - not to deny it. He was even somewhat proud.
Of course (and interesting enough I had this discussion a few days ago with german antisemites) there is some "logic" in killing all jews if you are mad enough to believe german propaganda. There is always some inner logic in madness. For some germans jewish people deserved their destiny and right after the war these germans were willing to tell so.
For years it was not uncommon to say
"After all their influence was huge in media"
or
"there were too many jewish bankers/doctors/lawyers in that time".
Even Max Domarus, the editor of Hitlers speeches and author of a biography wrote in "Hitler. Reden und Proklamationen" which is a standard until today
"Jews weren´rather popular in germany in normal times also. They had something that would evoke disapproval. They were importunate and had some special habits, for example in sexuality." (I know it´s a bad translation - if you wanna try it yourself start Vol I, p.35)
After a while, in the time of Adenauer, there was not too much interest in that subject. Nobody wanted to ask questions, listening to "old stories" or look deeper in the past - there was a new war at hand, a cold one with new frontiers and new allies. There was a growing economy and money to make.
This changed somewhat in the 60´s when Eichmann was captured and the Auschwitz-trials at Frankfurt/Main started. Holocaust became a story again, young germans began asking their parents "What did you do in the 3rd Reich?", students challanged their teachers/professors - this movement became the german version of 1968 and, of course, it was far left and talked about revolution. There was a lot of anger against the parent´s generation.
Interesting enough after that there was the first wave of really holocaust-denying literature in germany - Roth, Butz, Rieger of course Harwoods "
Did Six Million Really Die?"
Now there was some willingness to believe in germany, after the huge attack from the far-left on that subject arguments shifted somewhat form "Don´t mention the holocaust!" to "What holocaust?"
Right after the war nobody would have buyed that story, in the 50´s nobody wanted to hear anything about it, in the 60`s there was a denouncemnt of a whole generation, there was holcaust everywhere including Vietnam and in the 70´s the real denial began.
Besides: Given german laws at that time it was much more easier to deny it than to approve it!
This may have played a role too.
All I was writing about was west-germany. In the GDR this was another story. In communist germany there were no nazis at all, ordered by the gouvernment and of course propaganda. All nazis lived in western germany, so there was no really need for a discussion in society like in the FRG in the 60´s.
On the other hand the FRG disliked Israel a lot - there was a possibility to be antisemitic and a good citizen. It was not popular to broach that issue.
Today Holocaust-denial is forbidden by law in germany so it is not discussed in german forums. Germans modern neo-nazi-partys advise their members to avoid any discussion about that subject.
A german-speaking nazi site made a poll with more than 1.100 participants -
66 % believe there was no holocaust at all,
39 % say "yes, there was a holocaust"
(12% don´t believe in the hoax at all, 27% say it was not as bad as told)
http://forum.thiazi.net/showthread.php?t=12662
The denying fits well in the argumentation of the german neo-nazis.
"Jews control this, Jews control that, Jews everywhere and no wonder they tell you there has been a holocaust. That´s how far they go! How would that be possible if Jews didn´t control this and that? And we pay for it until today."
Sorry for the english, I hope you got the idea.
(And I got the point)