How do we know that anti-Zionist posters are Jewish?

How do we know that pro-Zionist posters are Jewish? Could they be Evangelical Christians? The lack of Kavod HaTorah and regard for Gedolim they spew is very suspicious.

I have the same question about Neturei Karta, although it does also apply to our resident trolls. How do we know they are Jewish? They’re definitely on Iranian and Qatari payrolls, but are they even Jewish?
Take some of its leaders, such as “Rabbis” Yisroel Dovid Weiss, Dovid Feldman, Yitzchok Deutsch, or any of its other prominent stochastic terrorists. Does anyone know who they are and where they come from?
Take a shul in Turkiye, for example. These shuls do exist, although not under the best of circumstances, so if you show up there unannounced, don’t know anyone, and have never communicated with them before, they’ll want assurance you don’t pose a threat. Generally in such circumstances, they’d ask you to recite a prayer in Hebrew to demonstrate your likelihood of being Jewish.
Meanwhile, Weiss and friends protest publicly on Shabbos. There’s a video of someone asking them if they know Aleinu, or one of several other prayers. They do not know it, which makes it all the more suspicious.
The main suspicion, though, is where they come from. Does anyone know of a firsthand source saying they knew any of its prominent members before joining? In which case, a few questions:
1) Who were Yisroel Dovid Weiss’s parents? Names please; referring to them as “Hungarian-born Holocaust survivors” is way too generic and doesn’t answer the question. Or any of these rabble rousers, who are they?
2) Which yeshiva did any of them go to? Which shul did their parents attend?
3) What were their jobs before NK? No prominent member of that terrorist organization has become prominent before age 40+. What did they do before that, and how did they get connected with NK?

My criticisms and doubts apply primarily to the branches in the US and UK. The Meah Shearim branch (e.g. Toldos Aharon and affiliated groups) is certainly Jewish, and their opposition to Zionism is more based on Messianic eschatology than politics. But for the ones based in Monsey and Stamford Hill, it’s mighty suspicious. So I ask, does anyone know the origins of these people?

Anything COULD be. But Jewish Satmar people like him do exist, so our assumption should be that he is real. Besides Iranian agents probably would want to target more worthwhile avenues, such as Christian’s or leftists.

The most suspicious part is that they claim to follow their gedolim, but when we here have a discussion on an issue, they are unable to go back to the gedolim and clarify the issues. We still do not know whether yeshivos have statistics on OTD in the army, or what was current path to non-Jewish government in EY and scores of other issues. I do not recall anyone saying on any topic here – I went back to Rosh Yeshiva and he clarified …