Judaism has a rich history of branches that needed to be pruned. False messiahs, etc.

Judaism is a deep spiritual tradition, but the people who follow it, Jews, are only human beings.

Sabbatai Zevi was a great leader, a unifier, of Jews, in the 17th century. As is always the case, there was abundant evidence that he was the messiah and he was fully accepted as such by many people. Until he wasn't. In fact there have been dozens of well known claimants to the messiah title.

The messiah, whoever or whatever it is, is closely tied to the legitimacy of authority in the Land of Israel. (The Land of Israel, the actual physical land, not to be confused with any government). Some religious Jews believe that the current overt political structure in the Land of Israel, a sort of democracy with political Jews maintaining their authority through force, is offensive. Others will interpret things in a way that justifies the current political state in the Land of Israel.

Zionism has little to do with Judaism.

The founders of the modern political state of Israel were not motivated by Judaism per se, they were largely motivated by anti Semitism. In Europe of the 19th and early 20th century, prejudice against minorities, including Jews, was widespread. In some places there were specific laws restricting the liberties of Jews and other minority groups. In addition to laws there was widespread simple prejudice that made life difficult.

So the actual state of Israel is Zionist, not Jewish.

Simply having a lot of Jewish citizens does not make Israel a "Jewish" state.

You can say that Israel is a Jewish state perhaps in the same sense that a particular deli is a Jewish deli. But you cannot say that Israel is a Jewish state in the sense that the Land of Israel or Jerusalem are Jewish.

No matter what politics are at any moment, Jerusalem is a primary Jewish locale, as is the Land of Israel. Their Jewishness has nothing to do with any particular politician, political party or government. That does not preclude either from also being a Christian and Muslim locale too. The distinction being between "the state", the political structure built around very short term interests, and the Land which is only polluted by politicians.

At this point some people will get clever with the definition of "Jewish". The essence of the "Jewish state" argument rests in the physical control of political infrastructure. Semantically a person can be deceptive and say "Jews in control means it is Jewish". But really, is that what "Jewish" means? Is that really the level to which the word "Jewish" has descended?

People anywhere, regardless of bloodline, have the basic human right to live free from the violence of others. The founders of Israel had that in mind when they created their state. The problem was not solved in their action, though, since they pursued that comfort for themselves alone and not for their neighbors.

After the holocaust was coined the term "Never Again".

The phrase has two utterly unrelated spirits, or senses. Sense one is "Never again to Jews (but to others, it's too bad but okay)", and sense two is "Never again.".

For many people, "never again" gave a kind of secular legitimacy to the state of Israel. In other words the state of Israel was a sort of monument to the spirit of "never again". But in which of the two senses, a person must ask? Looking at the actions of the state of Israel, both domestically and abroad, there is no question whatsoever that the state of Israel, its leadership from the start to the present day, has little interest in protecting any other group than itself. Countries are not humanitarian organizations, certainly, but in this case Israel loses any claim at least to representing Jewish values, which is significant.

The state of Israel has built numerous rhetorical defenses for its conduct. A common theme is that "Israel lives in a dangerous neighborhood" or "look at the atrocities committed by them". Again, as a country Israel has the same rights and vulnerabilities as any country. It can use language to construct defenses, it can use guns to silence critics etc. But it cannot use Judaism to defend misconduct. As a Zionist state it is a wonderful place in many ways. As a Jewish state it is a fraud that is becoming dangerous.