What Zionism is
Zionism is the belief that the Jewish people have the right to live as a nation in the Jewish homeland, where Jews have lived continuously for over 4,000 years.
That is not racism. It is national self-determination, the same right every other people claims in its historic homeland. French people have the right to a homeland in France. Is that racist? No. Simple.
You can fiercely criticise any Israeli government and still be a Zionist, just as you can criticise the French government while believing France is the homeland of the French. Neither is racist.
