The Prophet of Allah Jesus son of Mary (peace be upon him) will descend at the end of time and judge among the people with justice, following the Law of our Prophet Muhammad (peace be upon him). He will break the crosses and kill the swine. He shall put an end to the payment of the jizya. He will only accept Islam from the people.
The People of the Book, the Jews and Christians, will all believe in him before his death, after he descends at the end of time. Allah has stated, "There is none of the People of the book but must believe in him (as only a Messenger of Allah) before his death. And on the Day of Resurrection, he (Jesus) will be a witness against them." [an-Nisa, 4:159]
Allah has stated that all of the People of the Book, Jews and Christians, will believe in Jesus son of Mary (peace be upon him) before his death - that is, before the death of Jesus. That will be when he descends at the end of time as a judge and just caller to Islam, as shall be noted in the hadith describing his descent.
This is the meaning of the words [in the verse quoted above]. The context of the verse is demonstrating the stance that the Jews took toward Jesus (peace be upon him) and what they conspired to do against him. It also shows the way of Allah in saving Jesus and refuting the works of his enemies. The pronouns in the phrase, "believe in him before his death" must both refer to Jesus to be consistent with the context and so that the antecedents will be the same. It is confirmed in numerous authentic hadith, that have come through numerous chains and have reached the level of mutawatir [narration that has been reported through so many chains and from so many people that there is no way to doubt its authenticity], that Allah raised Jesus to the heavens. They also state that he will descend at the end of time as a just ruler and will kill the False Messiah [Anti-Christ].
Ibn Taimiya said, after quoting the numerous chains reporting Jesus' being raised to heaven and his descent at the end of time, "These hadith are mutawatir from the Messenger of Allah (peace be upon him). They have been narrated from Abu Huraira, Ibn Mas`ud, `Uthman ibn Abu al-as, Abu Umama, al-Nawas ibn Samaan, Abdullah ibn Amr ibn al-As and Hudahifah ibn Usaid (may Allah be pleased with all of them). These hadith contain indications concerning how and where he will descend."
One of those hadith is the following: Abu Huraira reported that the Prophet (peace be upon him) said: "By the One in whose hand is my soul, soon the son of Mary will descend upon you as a just judge. He will break the crosses, kill the swine and will put an end to the jizya. And wealth will spread to the extent that on one will accept it." Then Abu Huraira said, "Recite if you wish, "There is none of the People of the Book but must believe in him (as only a Messenger of Allah) before his death. And on the Day of Resurrection, he (Jesus) will be a witness against them."" [an-Nisa 4:159] [Al-Bukhari & Muslim]
In another narration from Abu Huraira, the Prophet (peace be upon him) said, "How will you be when the son of Mary descends among you and your leader will be from among yourselves?" [Al-Bukhari & Muslim] It is also confirmed in the Sahih from Jabir ibn Abdullah that he heard the Prophet (peace be upon him) say, "A group of people from my Nation will continue to fight in defense of the truth and remain triumphant until the day of Judgment." He also said, "Jesus, son of Mary (peace be upon him), will descend upon them and their leader will say (to him), 'Come and lead us in prayer.' He will say, 'No, Allah has honored this Nation by putting some as leaders over others.'" [Saheeh Muslim]
This hadith demonstrate that he will descend at the end of time and that he will judge according to the Law of our Prophet Muhammad (peace be upon him). They also show, without doubt, that there will be a leader for this nation at that time. Furthermore, there is no contradiction between his descending and the fact that the Prophet Muhammad (peace be upon him) is the seal of the prophets. This is so because Jesus will not be descending with a new law. To Allah belongs the decree, first and last. He does what He wills and rules as He wills. There is none to come after His Rule. He is the All-Mighty, All-Wise.