Anti-Zionism assumes that Israeli Jews are racist human rights abusers. This legitimises anti-Semitism and creates an environment where prejudice flourishes.
Even if anti-Zionism isn't itself anti-Semitic, it creates an environment where anti-Semitism can flourish.
Anti-Israeli expression creates an environment where anti-Semitism becomes more acceptable. In an environment where many people hold anti-Israel beliefs, they are less likely to challenge anti-Semitism when it occurs. This is reflected most prominent in Europe. In Europe, just 54% of respondents believe Israel has the right to exist as a Jewish state. Around 25% believe Jews have too much influence in business and finance. It is hardly surprising, therefore, that there is also a high rate of anti-Semitic and attacks against European Jews. In Paris, for example, in 2015, four people were killed during a siege of a Kosher supermarket. In Sweden, firebombs were planted outside a Jewish burial chapel, and in Denmark, also in 2015, a security guard was shot while guarding a bat mitzvah. Sadly, armed guards are often required outside European synagogues. There is evidently a direct correlation between anti-Zionism and anti-Semitism. Even if anti-Zionists are not explicitly anti-Semitic, they create an environment for anti-Semitism to flourish. Therefore, it is damaging to Jewish communities.
Demonstrating Europe has a large number of anti-Zionists and Europe has a large number of anti-Semitic attacks does not prove causality. Anti-Zionism does not create an environment for anti-Semitic attacks to take place. The two are entirely independent and unlinked. Firstly, there are many anti-Semites who actually embrace Zionism. In 1905, Arthur Balfour, the former British foreign secretary, supported the Aliens Act, which restricted Jewish immigration to the UK and was widely seen as an anti-Semitic bill. In 1917, he also asserted he was very much in favour of Zionism. The fact that the two beliefs can be held concurrently disproves any notion that anti-Zionism creates fertile ground for anti-Semitism. Anti-Semites come from all sides of the Zionism debate. Many argue for it and many against. Secondly, the vast majority of the anti-Semitic attacks which are carried out in Europe are carried out by radicalised Muslims. It would be a far more accurate statement to assert that "radical Islam" creates an environment in which anti-Semitism prospers, not anti-Zionism.
[P1] Anti-Zionism creates an environment in which anti-Semitism can thrive. [P2] Therefore, both are dangerous to Jewish people.
[Rejecting P1] Anti-Zionism has no impact on anti-Semitism.