Judaism, like any other religion, is stupid. We should be allowed to criticize it.
But if I post that I’m a Jew and you say that I’m not, that’s not criticizing the religion.
Are you fucking retarded? If I claim that I am Santa Claus and you point out that I am not, then that isn't attacking anything. That's simply pointing out a fact.
When you lie (and it is a lie, since you have been corrected about it on dozens of occasions), then using factually accurate data to correct your lie is called SCIENCE.
but I have nothing against Jews as a people.
The problem with this is that Jews are not a (i.e. one) "people". They are a collection of many different people(s) whose only truly common trait is the religion they follow. You can't describe Chinese Jews, African Jews and Israeli Jews as the same "people" simply because they practice the same religion. The idea of Jews as either a race or an ethnicity is a myth, and some of the best research proving it has been conducted by -- ironically -- Jews.