Anti-Semitism
Interviewer: So, are you guys as anti-Semitic as some might believe?
Matt Stone: You know, a lot of people have accused South Park of anti-Semitism, but I'm Jewish, and so I can say with some certainty that I am not anti-Semitic.
Trey Parker: I am, however.
Cartman, dressed as Hitler, leading a march to begin "the cleansing" of the Jewish community.
Since the inception of South Park, creators Trey Parker and Matt Stone poked fun at the Jewish community. Much of this comes from the character of Eric Cartman, who is constantly making fun of Kyle and his family for their Jewish faith.

"
Well, Kyle, appreciate you being so open with me about this, but as we know, you have a warped perception of reality because you�re jewish." - Eric Cartman
The Jewish ridicule was quite apparent in the episode titled "The Passion of the Jew." In this episode, Kyle is pressured by Cartman into seeing "The Passion" so that he can learn that the Jews were responsible for the death of Jesus Christ. Meanwhile, Cartman starts a "Passion" fan club, where the people believe a young boy has started a fan club to spread the word of Christianity. Cartman, on the other hand, has other intentions. Resembling Hitler, Cartman instructs the people to go see "The Passion" again and bring one person with them before they start "the cleansing."
"It's best we not say anything until they're on the train to the camps." - Eric Cartman
Cartman is not the only character who ridicules the Jewish faith. In the episode "Spontaneous Combustion" Father Maxi is speaking to the kids:

Priest: Boys, I haven't seen you in church lately.
Kyle: Well, I'm Jewish.
Priest: You're not too Jewish to worship Jesus, are you?
Kyle: I guess not.

Or from the episode "Big Gay Al's Big Gay Boatride":

Commentator: Wow! I haven't seen a Jew run like that since Poland 1938. (Referring to Kyle playing football)

From the episode "Mr. Garrison's Fancy New Vagina":

Basketball coach (to Kyle): No, you see, Jews can't play basketball. They're not tall or black enough.
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