why did adolf hitler feel strong desire to kill all the Jewish people in the world?
Hitler says in Mein Kampf that originally he hadn't given any thought to Jews and that they had just seemed Germans with some differences, and that he had found antisemitism mildly distasteful, etc.
But he was a Nationalist and later he found that they controlled the press, and he didn't like how they curried favour with the Austrian court, and were subtly malignant towards Germany, and were pro-France. Furthermore "Was there any form of filth or profligacy, particularly in cultural life, without at least one Jew involved in it? .... What had to be reckoned heavily against the Jews in my eyes was when I became acquainted with their activity in the press, art, literature, and the theatre. .... I now began to examine carefully the names of all the creators of unclean products in public artistic life. .... The fact that nine tenths of all literary filth, artistic trash, and theatrical idiocy can be set to the account of a people, constituting hardly one hundredth of all the country's inhabitants, could simply not be talked away.... .... The relation of the Jews to prostitution and, even more, to the white-slave traffic...."
He was convinced that the were behind internationalism and communism (Marx, Trotsky, Bela Kuhn, etc were Jews) and behind the protocols of Zion.
Hitler said the Jews are a race/people not just a religion. He believed they are culture parasites.
You'd really have to read his own account in Mein Kampf to get a better picture than I have not very well provided above. How/why he became anti-Semitic is is chapter 2 'years of study and suffering in Vienna', and his views about them being culture parasites further given in chapter 11 'nation and race'.
There was a news item couple of years ago claiming Hitler had some (north) African genetic ancestry. Maybe he has Hamite/Hamitic blood?
Many nationalists still believe today that the Jews are behind globalism, that they want world domination, with Israel as their base state ("Zionism", "Zionist Occupational Government"). The Jews have also been opposed for their usury.
Personally I think Revelation is right that the harlot "Babylon" rides the beast and controls world trade and is responsible for many wars and martyrdoms and murders. Haman's mother maybe?
It is disputed by some that there was ever really a holocaust gassing of 6 million Jews. They say they had to have concentration camps during the war, and that the intention was to ship them out after the war.
I think the bible says only a remnant 1/3rd of Jews will survive the tribulation and be saved.