Emmanuel Goldstein is the fictional creation of Big Brother and the party. Goldstein was created to be the symbolic enemy of the party and they use his image during the two-minute hate to channel and project all the feelings of hatred, frustration, and other toxic emotions. Goldstein might have an historical correlation also. Enotes criticism states that
Goldstein is reminiscent of Leon Trotsky the great enemy of Soviet leader Joseph Stalin who led an unsuccessful revolt and was later brutally murdered by Stalin’s men. It is no accident that he is a Jewish intellectual because dictators Stalin and Adolf Hitler deeply feared and hated the Jewish intelligentsia. (source)
Goldstein is another tool amongst many in Big Brothers' array of manipulation. In making a psuedo-communistic state in Oceania, Orwell is implicitly suggesting that communist Russia at the time of writing, was some sort of real life Oceania.
Goldstein is a fictional enemy of the state who is the subject of Oceania's Two Minutes Hate. But there are some other factors to consider when analyzing Goldstein's presentation to the people of Oceania.
First of all, Goldstein is presented as physically repulsive. Winston tells us, for instance, that he has a "face like a sheep," a "silly" nose and an overall air of self-satisfaction. This irritates the people of Oceania and encourages them to hate him.
Secondly, the Party gives Goldstein a voice but it is the voice of treason. According to Winston, Goldstein is presented as "abusing Big Brother...denouncing the dictatorship of the Party and...advocating freedom of speech." Even though the Party has falsified these statements, they directly contravene those of the Party and thus contribute to Goldstein's status as a repulsive and rebellious outsider.
Thirdly, Goldstein is presented as a man who lurks in the shadows, causing problems for the Party and the people of Oceania. As Winston states:
All subsequent crimes against the Party, all treacheries, acts of sabotage, heresies...sprang directly out of his teaching.
The Party, therefore, portrays Goldstein as a man who directly threatens the safety of Oceania's citizens. By doing this, it reinforces the view of Goldstein as a dangerous outsider. Again, it does not matter that these acts are fictitious because Goldstein is the Party's scapegoat and they must say and do whatever is necessary to maintain that idea.
Finally, the fact that Goldstein is Jewish is an interesting and significant point. By giving Goldstein a Jewish heritage, Orwell is making an important point about our history: like the Jews, Goldstein is persecuted and victimized for crimes he has not committed.