Hitler, one of the leaders of the Nazi Party had an extremely nationalist, racist and antisemitic view of Germany. His racial ideas and policies connected to extreme nationalism because he believed that the Germans were from a superior race and that all people that were not a part of that race should be exterminated.
Hitler believed that the jews were from an inferior race that they were destructive to the Germanic race and did not have a place in Germany.
Later on, Hitler applied the same rule to other groups such as homosexuals, disabled, gypsies and other minorities that did not fit his idea of the Aryan race. To do so, he created a series of laws and policies that removed rights from those people and allowed the holocaust to happen.