HASHKOFO-----apikorsus = apikores?

As far as whether if you believe apikorsus that automatically makes you an apikores, the answer is not always. Here are the rules:

1) Apikorsus (a.k.a. “meenus” a.k.a kefirah – the words are often used interchangeably) is anything that is contrary to the Torah's opinion, regardless of whether it contradicts one of the 13 Ikarim or not.*

2) Not everybody who says Apikorsus is himself an Apikores. As the Chazon Ish writes about a piece of apikorsus he saw in a certain sefer: "Even though the author was a Yorei Hashem, he worshipped Apikorsus unwittingly."

3) To be a full fledged Apikores yourself, which means we have no mitzvah to love you, - on the contrary, there is a Mitzvah to loathe you (“l’snoso”); we don’t return your lost items; your wine is yayin nesech; you lose your share in Olam Habah; you are, for all practical purposes, not part of klall yisroel, and you have the status of a goy regarding all privileges (even though you are still obligated to fulfill all the Mitzvos) – for that, you have to disagree with one of the 13 Ikarim, regardless of whether you are doing so on purpose or out of ignorance. That is, even if you don’t realize that you are disagreeing with them, you are still a full fledged Apikores, as Rav Chaim Brisker ZTL used to say: Nebach an apikores is oich an apikores "Someone who is an Apikores through no fault of his own is an Apikores nonetheless". If you knowingly disagree with anything the Torah says, meaning, you know the Torah says such-and-such, and then you say “The Torah is wrong,” you are in this category as well.

4) Even if you do not actually deny one of the 13 Principles, but merely are unsure about it, you are still a full fledged Apikores. You must be convinced of the absolute truth of these 13 Principles in order to get your share in Olam Habah and be considered part of Klall Yisroel, as per #3 above.

5) There is a disagreement between the Rambam and the Raavad regarding someone who, in the course of his Torah learning, makes an honest mistake, misunderstands something he sees in the Torah, and erroneously derives from the Torah a belief that is actually Apikorsus. The Rambam holds this person is an Apikores and the Raavad holds that he is not. **

5a) Even the Ravad, however, agrees that even though the person himself is not considered an Apikores, his mistaken belief is indeed considered Apikorsus.

6) Please see my post elsewhere on the site that explains why 4a above is not a contradiction to Rav Chaim’s rule of nebach an apikores is also an apikores.

7) Even Orthodox people who fulfill all of Torah and Mitzvos can be full-fledged Apikorsim. Said the Chazon Ish, “There are people whose homes are sufficiently kosher that you may eat the meat, the fish, and all of their food, but there’s only one food item you can’t eat: You can’t drink their wine, because their Hashkofos make it yayin nesech”. Even great Talmidei Chachamim can be Apikorsim. The Rambam states that even if a person has great wisdom and has great merits due to his Torah knowledge, he is still a full-fledged Apikores if he does not believe in the 13 Ikarim.

8) There is a belief held by many people that you have to know the whole Torah, or at least some great measure of it, in order to be an Apikores. This is a myth. There is no such thing. As long as you deny one of the Yesodei Hadas, one of the Fundamentals of our Religion, you are an Apikores. There is also a myth, believed by many, that there is “no such thing” as an Apikores nowadays. This, like the “kol hatorah kulah” myth, is a fairy tale. (Historically, they both cropped up as baseless rationalizations of religious Zionists who befriended and sometimes even raised to the stature of heros, atheist Zionist Apikorsim. Through these wishful ideas, they attempted to remove those atheist enemies of G-d and Torah from the category or Apikorsim)

8a) In order to preempt what I have heard on more than one occasion cited as “a source” for the above, the Chazon Ish does not say anywhere any such thing. On the contrary, on numerous occasions he declares people to be Apikorsim, including frum Jews , as per #7 above. What he did say is that the Halchacha of Moridin v’Lo Maalin – that you are allowed to kill an Apikores – does not apply nowadays, because we are not able to fulfill the prerequisite of properly giving them tochachah before hand, as well as the lack of open miracles nowadays.

9) Even though usually we have a rule that we try to be melamed zechus (judge favorably) on Jews, where an Apikores is concerned, the contrary is true. We are not melamed zechus at all. On the contrary, someone who refuses to curse the Apikorsim, is halachicly suspect to be an Apikores himself.