Two of the most common arguments for Israel are the Holocaust and the need to reward victims with their own country and the Biblical argument that G-d gave the holy land to the people of Israel.
Both arguments are good and true. The Holocaust indeed showed that a Jewish state was necessary and the Bible (and the Quran) indeed claim that G-d gave the holy land to the Jews.
However, the odd part about the arguments is not that they are made but by whom and why. They always come up in discussions about Israel but they are rarely used by Zionists and Israel's Jewish supporters. While they are at times used by non-Jewish supporters of Israel they are most often used by opponents of Israel as examples for the supposed flawed logic (and religious fundamentalism) of Zionists.
Most civilised (and wanting-to-seem-civilised) people reject religious fundamentalism. But the same people often do not want to equate religious fundamentalism with Islam. It's exceedingly difficult not to do that because fundamentalist Christians and Jews just don't stone women that often. However, religious fundamentalism is considered a bad thing among progressives and hence is the ideal representative for the progressives' theory of what Zionism should be.
And suddenly a secular socialist movement, Zionism, becomes Jewish fundamentalism and just as bad as Islamic fundamentalism. Hence, progressives assume, Zionism is all about some religious ideological fantasy of a god who allegedly gave the land to the Jews 2000 years ago. (For some reason "2000" is a number typically used. G-d knows why. Sorry, _nobody_ knows why.)
There are, of course, religious Zionists. And the Zionist movement certainly had a religious element. But the Zionist movement was not based on religion and certainly had nothing to do with the Holocaust that happened 60 years after the Zionist movement started in earnest.
The Zionist claim to the land of Israel is simply that the Zionists bought the land Jews settled on.
It has nothing to do with the Holocaust and it has nothing to do with religious fundamentalism.
The two arguments are only brought up by detractors so they don't have to address the ownership issue based on land titles and can instead propagate the theory that the land was owned by Arabs until stolen by Jews with European support to make up for the Holocaust.
The fact that most European Jews were dead after the Holocaust and that most Israeli Jews are refugees from Arab countries is ignored. For the progressive opponent of Zionism, the existence of millions of European Jews after the Holocaust is no less an obvious fact as is the apparent disappearance of middle-eastern Jews which have "lived in peace", as they say, with their Muslim neighbours for centuries. Israeli Jews, whether there parents fled Kurdistan from Arab invaders, Baghdad during the time when Iraq was allied with the Nazis, or Egypt during one of the many pogroms, are all European invaders that took Arab land. It seems as if progressives cannot even imagine that non-Arabs might own land in the middle-east which is an attitude seemingly at odds with their proclaimed multicultural ideals.
But for the progressive evil people are not those who do evil deeds, but the reverse is true. Evil deeds are done by evil people. If religious fundamentalism is evil, it doesn't mean that its proponents (for example Hamas) are evil but it means that evil people (like the Zionists) are religious fundamentalists. The best case scenario is that there are evil people "on both sides", as if any relevant number of Jewish fundamentalists existed who call for the extermination of all (or six million) Arabs or refer to Arabs as "monkeys and dogs". (Jews can be dicks. But we don't celebrate them for it.)
In this case the world is indeed as black and white as it looks at first. (Or is it genetically opressive and African-American?)