It's like trying to teach that 9/11 didn't happen. If folks want to believe it didn't , go speak to the folks who were there.
The problem with this statement is that less than 25 years from now, there will be no one left to go ask. As it is, it's hard to find anyone still living who remembers the horrors.
The ptovlem with the anti-holocaust nuts is that they started a few years too early; if they'd waited a few more years, there would be no one alive to nay-say them, and they could always resort to the "documents and photos were fabricated" line.
As it is, there are still a few who can show the number tattoos on their arms....