Antisemitism is a form of racism and/or religious persecution that has affected Jews around the world for over two millennia, the majority of whom are unaffiliated with the Zionist state of Israel. It would be cool if you stopped making fun of it.
I don't think they're making fun of antisemitism itself. People can refuse to indulge the spurious accusations of antisemitism Israel's right-wing throws out in knee-jerk fashion every time it is criticized, and still take antisemitism seriously as a real and dangerous phenomenon with a long history. I understood the comment above yours as making fun of the former, not the latter.