Yes, but its beside the point. With Jesus being jewish, its jews who 'tricked' people into worshipping the demiurge. Its that classic "jews are tricksters, christains are just people who got tricked" bullshit. And, just overall, a lot of their teachings are just, inherently 'twisting' a lot of jewish era mysticism around, which is of course funny in a way, considering how much they also steal from jewish mysticism.

Regardless, all of that is more or less history; I don't think people calling themselves gnostic today are generally specifically anti-semetic. And its not like Christianity of the era was particularly accepting of jews.