I start with a statement that many will find counterintuitive and is this: since Zionism is a non-religious political movement belonging to the sphere of politics according to its own founders, to oppose Zionism a priori does not make one a Judaeophobe and anti-Semite of necessity. Said in other words, in theory, it is possible to be an anti-Zionist without hating Jews as a people or as a believers of their particular religion and at the same time, there is no obstacle in principle impeding an otherwise tolerant state to oppose Zionism and to protect the civil liberties of the Jewish people in their midst.
Unfortunately Ad Orientem: Anti-Zionism & Anti-Semitism also says "Please leave your comments at Vivificat!", and that is something I find difficult to do, because an Orthodox perspective on the matter must differ from a Catholic perspective, and operates with different asumptions. I think the assumptions of the Vivificat! article are flawed, not merely because they are Catholic, but because they are approaching it from a different end.
In my experience (which is no doubt fairly limited) the link between Anti-Zionism and antisemitism has been made by apologists for the government of the state of Istrael, who denounce any criticism of any policy of the government of the state of Israel (such as the bombing of Lebanon in 2006) as "antisemitic".
And if that is what "antisemitism" has come to mean, then I have no hesitation is saying that I think "antisemitism" is a thoroughly good thing.
I don't believe, however, that that "antisemitism" has come to mean that, or that it ought to mean that. I believfe that those who make propaganda for the government of the state of Israel have been twisting the meanings of words.
But that is what all warmongers do. Criticism of the Israeli bombing of Lebanon in 2006 have been described as "antisemitic" (on the grounds that "anti-Zionism is anti semitism"), just as critics of the US bombing of Iraq in 2003 and of Yugoslavia in 1999 have been described as "anti-American".
The Israel apologists also accuse those who criticise any policy of the government of the state of Israel of denying Israel the right to exist, as if the right to commit mayhem is an essential part of the right to exist.
There's no arguing with such people, and I've given up trying. I do not believe that criticising the policies or actions of the government of a state means that one denies that state's right to exist, but then, I don't believe that the right to exist includes the right to commit mayhem.
We had the same kind of attitudes in South Africa back in the 1960s. People who criticised the apartheid policy of the South African government were denounced by the government and its appologists as "anti-South African". But they believed that it was not possible for South Africa to exist without apartheid. They confused the government of the state with the state itself.
So much for my experience.
But one needs to go deeper and examine the roots of Zionism, which was a form of nationalism that arose in central Europe, and partly grew out of the romnatic movement in Germany. In this sense Zionism is akin to Hellenism, the Greek nationalism that arose from much the same roots. And there were other Balkan nationalism too, and others in Eastern Europe. Zionism, Hellenism and the other Balkan nationalisms wanted to establish "homelands" in territory under the rule of multinational empires. In most cases this was the Ottoman Empire, and in some cases the Austro-Hungarian Empire, the Prussian Empire, or the Russian Empire (e.g. Polish nationalism). One could even say that in South Africa Afrikaner nationalism has similar philosophical roots.
In some ways, Zionism is to Judaism as Hellenism is to Orthodoxy. Just as there are those who say "Antizionism is antisemitism", there are those who say that "Hellenism is Orthodoxy and Orthodoxy is Hellenism". And there are others who have tried to coopt religion for that kind of nationalism. The Roman Catholic Church is not exempt from this -- Croatian nationalism is not all that disssimilar from Zionism either.
I've written about this elsewhere, in an article on Nationalism, violence and reconciliation, though that link will no longer work after 26 October 2009, when Geocities closes.