The most effective way to vilify Israel with progressive people is by accusing her of racism, apartheid, ethnic cleansing, and so on. All of these accusations have to be somewhat creative because none of these characteristics actually apply to Israel in anything like their normal senses (indeed, Israel is one of the least racist societies around).
It’s worth pointing out, though, that they do apply quite well to Palestinians and other Arabs.
Take ethnic cleansing. A great deal of criticism is aimed at Jews who insist on trying to live in Hebron, in the midst of many Palestinians who don’t want them there. In their very faces, so to speak. What is often ignored is that Jews had lived in Hebron for hundreds of years, until 1929, when Hebron had 800 Jews. In that year, an Arab pogrom killed 67 of them, injured many more, and drove the rest out of the city. Many were killed horribly, with instances of rape, mutilation, and torture documented.
Another occasion of ethnic cleansing was 1948, when the many Jews who had lived in East Jerusalem and other areas captured by Jordan were forcibly driven out (and many were killed in the process, too). The Jewish quarter of Jerusalem was destroyed, Jewish tombstones torn up and used as paving and for latrines, synagogues were ruined. Jews were not permitted to live in these areas or indeed to worship at the Wall until Israel captured it again in 1967.
Apartheid is the forced separation of racial or ethnic groups for racist reasons. For example in Saudi Arabia, there are areas (near Mecca and Medina) which may not be entered by non-Muslims, and Jews are not permitted to enter the country, even as tourists. The practice of Christianity is forbidden in the kingdom, and Christian airline employees have been barred for carrying Bibles or wearing crosses. If one wants to include gender apartheid, women may not drive or go out unaccompanied or uncovered. Homosexuality is punished by death in Saudi Arabia.
And Arab racism…well, start by considering the Hamas Charter, a compendium of antisemitic hatred. Then look at some of their antisemitic cartoons. Ask the Egyptians about the blood libel, the protocols, etc. And it’s impossible to leave out mention of the genocide against black Africans perpetrated by the Islamic government of Sudan.