Does Judaism permit hating others (like hating anti-Semites)? Are Jews allowed to have grudges? Are Jews allowed to release the anger (ie is it encouraged or discouraged)? Why or why not? What are the prohibitions/restraints when it comes to releasing the anger, how do you know?
ב"ה Shalom Your question is seemingly innocent, but it is actually quite complex, touching upon philosophical issues and other aspects of the Torah. To answer completely would require a lengthy treatise, so I will just touch upon some major points. I will relate to things first on the national level, and I will point out if I refer to the personal level. 1. Does Judaism permit hating others? The hate Judaism permits, is not one on a simple level of an outburst of emotions. The hate Judaism permits is when there is a factor which hinders the service of G-d by the Jewish people. That is the time for the the Jewish people to become zealous to be G-d's nation and fulfill his will. If someone comes in the way of that goal by attempting to hurt us physically or otherwise then the Jewish people must stand up against those who hate them, who are actually the haters of G-d in order that G-d be served and his veneration be magnified. ( Messilat Yesharim Chapter 19.) Therefore, there are of are the Mitzvot in regard to Amalek and the vengeance which Yisrael took against Midyan (Bamidbar 31:2) 2. On the personal level, a Jew should not have a grudge against a fellow Jew. This is written explicitly in the Torah. (Vayikra 19:18). 3. The Tanach looks down upon anger. See for example Kohelet 7;9, 11;10). The Talmud also speaks against anger. See for example Nedarim 22b. 4. As far as dealing with anger, there are many books on ethics which deal with the issue of anger and how to manage anger. I am familiar with a good book in Hebrew called "Erech Apaim" written by Rav Avraham Yellin z"l. I'm sure there are scores of books available in English as well. All the best