Before I get into this area let me clear out some semantic issues: I am calling the people who have been widely known as Jews "Jews." Yes there is the Khazar theory. It very well may be correct. I don't know. There is also the theory that "Jew" is simply a voluntary self designation. I went along with that notion for a while. I now think it's absurd.
I'm pretty sure the Jews, me included, are not "pure" descendants of King David and his crew. If we were it wouldn't really matter anyway. As far as I know over 150 years ago the term antiSemitism was coined as an alternate to "Jew hatred" by people who hated Jews. It's what they wanted to be called. I searched in vain in Google but I remember reading of a Hitler associate saying that Jesus Christ was the first antisemite, and of course this nazi was identifying his movement with Jesus.
I remember in my High School days how me and the other Jewish nerds followed Paul Krassner's " Realist " magazine with its attacks or criticism if you will on Christianity There' plenty of criticism of Christianity and Islam to be found. A lot of it may be valid. A lot of it is written by peole who have Jewish names too.
Well then, what's wrong with harsh criticism of Judaism? What's wrong with attacking the politics of the Jewish community? Or its class character? Or its mythology? What's wrong with any of that? I'd say if the criticsm is false and dishonest then that is wrong.If it's innacurate but posed by someone with wrong information that's a little different thing. If it's accurate that's good. If it also can help make the world a better place it's great. If on top of all that it can help Jewish people to understand some part of reality that they never understoo and if the criticism helps them to become better people with better interaction with fellow human beings that would be a bull's eye.