Why did Hitler want to kill everyone not Aryan?

Who knows? Maybe not even Hitler himself knew exactly? And even though most people (including me) consider him sick, crazy and everything else that comes to our minds and is close to phycho, he had his opinion. Everyone is free to choose his political and religious understandings, even though were not the same as somebody else's. What he did he thought was right. Maybe he considered everyone else danger to Aryans or "not worthy living" because of their understandings? Whatever his cause was, he was ready to die for it. And so he did, suiciding himself in 1945, when WWII ended.