Was he a shrewd politician who picked up on a common idea at the time? Was he a true believer who brought his message to the people?
Not to dissuade more answers but "What did Hitler think about [x]" is one of the most popular questions and there are plenty of answers to various iterations of it in the FAQ in the sidebar.
Of particular interest might be this one specifically asking about anti-Semitism, answered by u/commiespaceinvader