Was Rabbi Hillel a Heretic?

There is a surprising statement in the Talmud that, at least initially, denies one of the fundamental principles of Jewish faith. The question, though, is what did the statement mean?

Sanhedrin (99a):

Rabbi Hillel said: There is no messiah for Israel for he was consumed in the time of Chizkyahu. Rav Yosef said: May Rabbi Hillel's Master forgive him. Chizkiyahu lived during the First Temple while Zechariah prophecied during the Second Temple.

Who is this Rabbi Hillel? R. Aharon Hyman (Toledos Tanna'im Ve-Amora'm, vol. 1 pp. 362-375) lists 14 different people named Hillel who appear in the Talmud. He attributes this statement to Hillel II (late second century), grandson of R. Yehudah Ha-Nasi and younger brother of R. Yehudah Nesi'ah I. It seems from the Gemara that Rabbi Hillel accepted the concept of a messiah but limited it to a time period that had already passed, to which Rav Yosef pointed out the Zechariah's prophecies of a future redemption seemed to disprove.

What did R. Hillel mean and how could he deny Zechariah's prophecies?

1. Rashi (ad loc.) explains that R. Hillel accepted the concept of a future redemption but merely held that there will be no individual who will bring that redemption. Rather, God will do it without a human messenger. If so, the debate with Rav Yosef was about whether Zechariah's prophecies necessarily entail a messiah or can be understood as foreseeing a redemption by God alone. R. Ya'akov Ibn Chaviv, in his introduction to Ein Ya'akov, and the Maharal (Chiddushei Aggadah, ad loc.) follow this approach.
   
   
2. R. Moshe Ha-Levi Abulafia (Yad Ramah, ad loc.) begins by suggesting that R. Hillel denied any redemption but then said that some explain that R. Hillel was only denying the person of the messiah (like Rashi), which he disputes. According to R. Abulafia, it is unclear how R. Hillel understood the prophecies of Zechariah.
   
   
3. Rabbenu David Bonfil, a student of the Ramban, explains in his commentary to Sanhedrin (ad loc.) that R. Hillel was saying that we will go straight to the period of the World-to-Come and skip the period of redemption known as the Messianic Era, in which there will be battles and the messiah will rule as king until the dead are resurrected (this follows the Ramban's views and not the Rambam's). He is not denying the coming of the messiah but stating that the process of redemption will be condensed. Presumably, R. Hillel believed that Zechariah's prophecies can be interpreted as referring to the World-to-Come.
   
   
4. R. Yosef Albo (Sefer Ha-Ikkarim 1:1) suggests that R. Hillel was not denying that the messiah will come; he fully believed in it based on a tradition. Rather, he was saying that there is no proof for this belief from the Bible. R. Albo then rebuts this explanation and explains that R. Hillel denied the concept of the messiah. However, he was not a heretic because he accepted the bare minimum of beliefs (God, Torah and Reward & Punishment) and only mistakenly rejected this. The Radbaz (Responsa 4:186) takes this same general approach. It is unclear, according to this approach, how R. Hillel understood Zechariah's prophecies.
   
   
5. R. Avraham Chaim Schorr (Toras Chaim, ad loc.) seems to explain that R. Hillel believed in a messianic redemption but that it will occur without miracles, because all of the miracles already occurred. Rav Yosef argued that Zechairah prophesied miracles and therefore they must happen. The dispute, then, was over the interpretation of Zechariah's prophecies.