Believing Jesus is real does change reality even more than not believing the holocaust. All countries are blessed by God, and believing in Jesus not only receives God's blessings, but also shapes and dictates the morality of that nation. White nations that don't believe in God are garbage nations that get subjugated by White nations that believe in God. Look at what King Alfred the Great did to the vikings, for example.
It does matter that they believe the holocaust is real. If they ever stop believing, the lie will cease.