In the chapter of Chelek, we learned the previous Mishnah, and now the Mishnah proceeds to list people who were highly prominent in the Tanach. Given their prominence and importance, and given their greatness in certain respects, one might have thought that they would certainly have a portion in the World to Come - but this is a mistake. They do not have a portion, because their actions in other respects were so terrible that they completely lost their World to Come. The main problem is that they caused the masses to sin, and therefore even repentance in and of itself is not sufficient to repair the evil they caused to the entire world.
The wording of the Mishnah: "Sheloshah melachim ve'arba'ah hedyotos ein lahem chelek la'Olam Haba" - Three kings and four commoners do not have a portion in the World to Come. This refers to three kings from the kings of Israel, and four 'hedyotos' - meaning people who are not kings. The term 'hedyot', as it usually does everywhere, indicates a level one degree lower than the previous level: these are prominent individuals who accomplished significant things of great importance, except that they caused such great evil that they do not have a portion in the World to Come.
The Three Kings:
Yarovam: The man who caused the division of the Jewish people into two kingdoms - the Northern Kingdom, Israel, which was his, and the Southern Kingdom, Judah. This happened after the passing of King Shlomo, when Rechavam caused great dissatisfaction among the people, and Yarovam took the opportunity to divide the nation. Yarovam set up two golden calves, two idols, in Beis El and Dan, and stated that these idols represented Hashem who took Israel out of Egypt, and that they should worship at these sites instead of at the Beis HaMikdash. This terrible act caused the masses to sin, and therefore Yarovam is counted in the list of the worst of the worst.
Achav: His severity is greater than that of Yarovam. By Yarovam there was indeed idolatry, but in the format of serving Hashem through an idol. Achav married Izevel the Phoenician, who was from Sidon (Phoenicia - roughly the area of modern-day Lebanon), and she brought in the Phoenician idols, spearheaded by the Tyrian Baal, as well as the Asherah. Baal was the central god in the Phoenician pantheon, while regarding the Asherah it is not sufficiently clear what it was - a female goddess or a ritual object associated with trees.
Izevel sought to completely uproot the service of Hashem, the God of Israel, and replace it with the Phoenician idolatrous system. Achav did not stand against her; on the contrary, he was the other half - albeit the weaker of the two - of that powerful duo that set out to kill all the prophets of Hashem. One hundred prophets were saved and hidden in caves, and of course, Eliyahu the Prophet stood against them.
In summing up their lives, in chapter 21 of Melachim I, it is stated: "Rak lo hayah che'Achav asher hismaker la'asos hara be'einei Hashem asher hesisah oso Izevel ishto" - There was none as evil as Achav, who sold himself to do evil in the eyes of Hashem through the incitement of his wife Izevel. Achav waged war against the prophets of Hashem and against Hashem Himself.
It is true that from the verses it emerges that after the confrontation at Mount Carmel, Eliyahu came to Achav and informed him of his sentence, and Achav submitted: he removed his shoes, wore sackcloth, and was extremely distressed by the entire situation. Scripture testifies that this somewhat delayed the destruction of his family until after his death, but this is not enough. Repentance can always be done, but when a person causes others to sin - how much more so the entirety of Israel - the repentance repairs him, but it does not repair the damage he caused. This damage was too great to be repaired, and therefore Achav does not have a portion in the World to Come even though he tried to repent at the end of his days.
Menashe: A king at the end of the First Temple period, the son of Chizkiyahu. Chizkiyahu fought heroically to eradicate all idolatry from the Land of Israel and brought the people to a spiritual revival, while his son Menashe was a terrible person and brought the idolatry back. Even though in the second half of his life he tried to do a sort of repentance and repair what he had ruined, it was too little, too late. Menashe literally destroyed the Jewish people, and even after twenty-two years, when he was taken to Babylon and returned and tried to fix things, it did not help, and therefore he lost his portion in the World to Come.
The Opinion of Rabbi Yehudah Regarding Menashe:
Rabbi Yehudah disagrees and holds: "Menasheh yesh lo chelek la'Olam Haba" - Menashe does have a portion in the World to Come. He truly tried to mend his ways, and indeed received a portion in the World to Come. His proof is from the verse in Divrei HaYamim, that when he was in captivity, Menashe prayed to Hashem: "Vayispallel eilav" - he prayed to Hashem; "vayei'aser lo" - he pleaded and begged; "vayishma techinaso" - Hashem heard his supplication; "vayasiveihu Yerushalayim lemalchuso" - and He returned him to his throne in Jerusalem. We see that the Holy One, blessed is He, answered him and returned him to his kingdom, and from here we learn that he repented and repaired what he had damaged.
They answered him: "Lemalchuso heshivo, velo lechayei HaOlam Haba heshivo" - To his kingdom He returned him, but He did not return him to the life of the World to Come. It is true that the Holy One, blessed is He, restored him to his crown and kingdom in Jerusalem, but He did not restore him to his portion in the World to Come. In other words, Menashe caused too much damage for his own repentance to repair, and therefore he lost his World to Come, as was explained regarding Achav.
The Four Commoners:
These are four people who were not kings, and they are famous in the Scriptures, yet nevertheless they do not have a portion in the World to Come. The knowledge of this is based on verses and on homiletic expositions of the verses, and we will present them here briefly.
Bilaam: Bilaam the wicked, the prophet whom Balak asked to curse the Jewish people. The Holy One, blessed is He, spoke with him, he was a prophet, and according to the words of Chazal, in certain respects his prophecy was equal to that of Moshe Rabbeinu and even surpassed it, and therefore one might have thought that he has a portion in the World to Come. It is worth noting that Bilaam was not Jewish, and one might have thought that he would merit a portion due to his connections with the Holy One, blessed is He. But he does not have a portion, because of all the wickedness he committed. The proof of this is from the verses: he said, "Tamos nafshi mos yesharim usehi achrisi kamohu" - I will die the death of the upright, a natural and normal death, and my end will be like the rest of the Jewish people. However, according to tradition, this is not what happened: Pinchas ben Elazar ben Aharon HaKohen is the one who killed Bilaam, and it turns out that he did not die a normal death, nor did he merit a portion along with everyone else.
Doeg: The advisor of King Shaul. When David fled from Shaul, he arrived at the city of Nov, a city of kohanim, and found refuge there. Achimelech the kohen gave him food and provisions, even giving him the sword of Goliath and inquiring for him of the Urim VeTumim. Doeg reported to Shaul that Achimelech and the people of Nov supported David; Shaul understood this as a sort of rebellion, and ordered Doeg to kill all the kohanim in Nov - and eighty-five kohanim died. For this, Doeg loses the World to Come. It is worth noting that the Rambam, in discussing the sin of lashon hara, brings the story of Doeg as proof of its severity, since it was Doeg who told the lashon hara to Shaul.
Achitofel: Originally the advisor of King David, and he was extraordinarily talented. Scripture says that consulting with Achitofel was like inquiring of Hashem Himself, meaning like inquiring of the Urim VeTumim. When Avshalom the son of David rebelled against his father, Achitofel joined his side and advised him how to rebel against David, including to cohabit with David's concubines and to try to kill David. Achitofel, a wicked person who rose up against David, loses the World to Come.
Geichazi: The servant of Elisha the Prophet, who according to tradition committed many evil deeds, the most prominent of which is explicit in Scripture. Naaman, the army general of Aram to the north of the Land of Israel, was stricken with tzaraas and came to be healed, and Elisha treated him. Naaman offered to pay, but Elisha refused and said that this is not what he seeks: he is not doing this for the money, but to help, as a servant of Hashem and as a prophet. Through this, a great kiddush Hashem was made. However, Geichazi ran after Naaman and told him that Elisha had changed his mind and was asking for money. There was a tremendous chillul Hashem in this, nullifying the kiddush Hashem that Elisha had made - and Geichazi was the cause of it. Geichazi committed another series of evil deeds according to tradition, and for his chillul Hashem and the rest of his terrible behavior, he too loses his portion in the World to Come.
In summary: The Mishnah listed three kings - Yarovam, Achav, and Menashe - and four commoners - Bilaam, Doeg, Achitofel, and Geichazi - who do not have a portion in the World to Come. The common denominator among them is that they were prominent and important people, yet nevertheless they caused the masses to sin or caused a chillul Hashem. Because of this, even the attempts at repentance by Achav and Menashe did not help, since repentance repairs the one who does it, but it does not repair the damage caused to the masses.