1) A PENITENT, FORMER-APOSTATE KOHEN
OPINIONS: The Mishnah states that Kohanim who served as priests in the temple of Beis Chonyo are disqualified from serving in the Beis ha'Mikdash, and it goes without saying that Kohanim who actually served Avodah Zarah are disqualified. The Mishnah derives this from the verse, "The priests of the altars [of idolatry] shall not go up onto the Mizbe'ach of Hash-m in Yerushalayim" (Melachim II 23:9). The verse concludes, however, that such Kohanim do not become disqualified from eating the Matzos of Menachos (and other Kodshim).
What is the Halachah with regard to an apostate Kohen's right to recite Birkas Kohanim?
(a) TOSFOS (DH Lo Yeshamshu) quotes the SEFER HIZHIR as saying that such a Kohen may neither recite Birkas Kohanim nor receive the first Aliyah to the Torah. The Torah says "v'Kidashto" -- "and you shall make him holy" (Vayikra 21:8). By turning against Hash-m, the apostate Kohen desecrated his Kedushah and is no longer entitled to the privileges granted by the Kedushah of Kehunah. (See also TUR OC 128:37 in the name of RAV NATRUNA'I GA'ON NATRUNAI GA'ON.)
This is also the ruling of the RAMBAM (Hilchos Nesi'as Kapayim 15:3) and the RAVYAH in the name of the TESHUVOS HA'GE'ONIM (quoted by the HAGAHOS MAIMONIYOS). The Rambam adds that a Kohen who worshipped Avodah Zarah may not recite Birkas Kohanim even if he was forced to serve Avodah Zarah or if he did so unintentionally. The Rambam quotes the Mishnah here and explains that reciting Birkas Kohanim is equivalent to performing the Avodah in the Beis ha'Mikdash, as the verse says, "l'Sharso ul'Varech bi'Shemo" -- "to serve Him and to bless in His name" (Devarim 10:8).
The KESEF MISHNEH, however, questions the source of the Rambam's ruling. Although the Gemara discusses the case of a Kohen who served Avodah Zarah unintentionally, it does not discuss the case of a Kohen who was forced to serve Avodah Zarah. Perhaps in such a case the Kohen does not become disqualified from serving in the Beis ha'Mikdash! The Kesef Mishneh concludes that the Rambam's source for this statement is unclear. In the BEIS YOSEF (OC 128:37, see also BEDEK HA'BAYIS), he adds that although the Rambam writes this with regard to a Kohen who was forced to serve Avodah Zarah, the Rambam does not write this with regard to a Kohen who was forced to convert. Perhaps such a Kohen may recite Birkas Kohanim.
(b) Tosfos quotes RASHI as saying that such a Kohen may recite Birkas Kohanim. The source for Rashi's opinion happens to be the Gemara here. The Mishnah states that such Kohanim are considered Ba'alei Mumim, Kohanim who are disqualified from serving because of blemishes. Although a Kohen with a Mum is not allowed to serve in the Beis ha'Mikdash, no Halachah prohibits a Kohen with a Mum from reciting Birkas Kohanim (unless the Mum is on his hands; see Megilah 24b). Moreover, the Mishnah states only that such Kohanim may not serve in Yerushalayim. This implies that such Kohanim were permitted to serve in other places where the Mishkan resided, such as in Shilo, Nov, and Giv'on (see Zevachim 112b).
The Hagahos Maimoniyos quotes RABEINU GERSHOM, the SEMAG, and RABEINU SIMCHAH who agree with Rashi. He adds that although the SHE'ILTOS D'RAV ACHAI GA'ON (Parshas Korach) also rules that a Kohen who converted may not recite Birkas Kohanim, Rabeinu Simchah understands that the She'iltos there refers only to a Kohen who did not do Teshuvah.
HALACHAH: The Beis Yosef (OC 128:37) concludes that one may rely on the lenient opinion that a Kohen who converted and then repented may recite Birkas Kohanim. This is also the opinion of the BACH, REMA, and many contemporary authorities (see SHONEH HALACHOS 128:70, TEFILAH K'HILCHASAH 14:19, and BEIN YISRAEL L'NOCHRI OC 3:27), although there are many who argue. However, as quoted in the name of Rabeinu Simchah and the She'iltos above, a Kohen who does not repent may not recite Birkas Kohanim. (Y. MONTROSE)
2) OFFERING KORBANOS FOR NOCHRIM OUTSIDE OF THE BEIS HA'MIKDASH
QUESTION: The Gemara records a dispute between Rebbi Meir and Rebbi Yehudah about the service performed in the temple of Beis Chonyo. Rebbi Meir says that the service there was performed for Avodah Zarah. Rebbi Yehudah says that Chonyo brought Korbanos there l'Shem Shamayim.
TOSFOS (DH v'He'eleh) asks that the opinion of Rebbi Yehudah is problematic. According to Rebbi Yehudah, how could Chonyo have knowingly offered Korbanos there l'Shem Shamayim? The Torah explicitly forbids the bringing of Korbanos outside the Beis ha'Mikdash!
Tosfos answers that Chonyo did not offer his own Korbanos. Rather, he offered the Korbanos of Bnei Noach who brought their pledges of Nedarim and Nedavos to him.
The explanation of Tosfos is difficult to understand. Rebbi Yosi states in Zevachim (45a) that although a Nochri is not prohibited from bringing Korbanos to Hash-m outside the Beis ha'Mikdash, a Jew is forbidden from bringing the Korban of a Nochri outside the Beis ha'Mikdash just as he may not bring his own Korban outside the Beis ha'Mikdash. Accordingly, even if Chonyo was offering the Korbanos of Nochrim, he still was transgressing the prohibition against offering Korbanos outside the Beis ha'Mikdash! How does the answer of Tosfos justify Chonyo's offerings?
(a) The TZON KODASHIM answers that the view of Rebbi Yosi in Zevachim is the subject of the dispute between Rebbi Meir and Rebbi Yehudah. Rebbi Meir agrees with Rebbi Yosi, and therefore he finds no way to justify Chonyo's actions. It must be that Chonyo was bringing offerings to Avodah Zarah. Rebbi Yehudah, however, argues with Rebbi Yosi and maintains that a Jew is permitted to offer Korbanos for Nochrim outside the Beis ha'Mikdash. Rebbi Yehudah therefore explains that Chonyo's actions were l'Shem Shamayim.
(b) Alternatively, the Tzon Kodashim and the SEFAS EMES answer that Tosfos does not maintain that Chonyo actually offered the Korbanos. He merely instructed the Nochrim how to bring the Korbanos. The Gemara in Zevachim (116b) explicitly states that this is permitted.
(c) The KEREN ORAH in Zevachim (45a), the MIKDASH DAVID (27:9), and the CHAZON ISH (41:14) interpret the statement of Rebbi Yosi in Zevachim differently. They understand that Rebbi Yosi is saying that a Jew is forbidden to offer the Korban of a Nochri outside the Beis ha'Mikdash if the Korban was dedicated to be brought in the Beis ha'Mikdash. If the Nochri originally dedicated the Korban in order to bring it somewhere else, then a Jew is permitted to offer the Korban for him. According to this understanding of Rebbi Yosi's statement, the Korbanos that were brought in Beis Chonyo were dedicated to be brought there and not in the Beis ha'Mikdash. Although this does not seem to be the opinion of Tosfos in Zevachim (116b, DH Asur), it could be the opinion of Tosfos here. (See HAGAHOS MAHARSHAM, who gives a novel answer in the name of the YE'AROS DEVASH.)
(d) The RAMBAM (in Perush ha'Mishnayos) is not bothered by Tosfos' question. The Rambam explains that Chonyo definitely transgressed the prohibition against bringing Korbanos outside the Beis ha'Mikdash. The only discussion in the Gemara is whether he brought his Korbanos l'Shem Shamayim (even though he transgressed an Isur every time he offered a Korban) or whether his intention was to serve Avodah Zarah.
The MAHARSHA cites a strong proof for the opinion of the Rambam. The Gemara here infers that the Mishnah (109a) maintains, like Rebbi Yehudah, that Beis Chonyo was not a place of Avodah Zarah, since the Mishnah says that Kohanim who served in Beis Chonyo may not serve in Yerushalayim, "and it goes without saying" that Kohanim who actually served Avodah Zarah are disqualified, implying that Beis Chonyo was not a place of Avodah Zarah. According to all of the abovementioned opinions in Tosfos, what did the Kohanim in Beis Chonyo do wrong such that they became disqualified from serving in the Beis ha'Mikdash? According to the Rambam, the Kohanim transgressed the prohibition against offering Korbanos outside the Beis ha'Mikdash, and therefore they became disqualified from serving in the Beis ha'Mikdash. (Y. MONTROSE)