Holocaust cannot be denied, but also stories are easy to write and facts can be made up.

One story is : Israel is the promised land, and Jewish are coming back to their land.

The other story is:
Jewish want to stole the Palestinian land, and to do this they needed some sort of legitimacy (we take your land by force, but.. we are the victims here), so if you are a thief, you're probably a liar too, that's why some people deny the holocaust.

For me the story is very clear : It's a war (they both choose so), the winner takes what he want, so please Fight.