But if nobody rejects or refutes the previous validity of the ex-president...
But if nobody rejects or refutes the previous validity of the ex-president, and if that ex-president is not calling people to swear their allegiance now to him, nobody can say that just by helping the present president, the ex-president is breaking the tenure of the office of the ruling president. Thus, if Prophet Jesus (a.s.) during his second advent were to call people to believe in him or if somebody was to reject even his previous prophethood, it will be against the Islamic belief.
But as Prophet Jesus (a.s.) at that time will not call people to believe in him, the Muslims will not be required to believe in a new Nubuwwah (Prophethood). They will be required to keep the same belief in his previous Nubuwwah (Prophethood) which they do have even today and which even Al-Mustafa (S) had had. Thus his second coming will not affect the Khatm an-Nubuwwah (Finality of the Prophethood) neither today nor in the days to come.
The fourth thing which is clear from these traditions and other numerous similar traditions is that Dajjal, who will be annihilated during the second advent of Prophet Jesus (a.s.), will be from among the Jews, and will present himself as Messiah. It is necessary to mention that after the death of Prophet Solomon, Bani Israel's history goes from one fiasco to another.
At last, after the captivity in Babylonia and Syria, they were scattered everywhere; and their prophets gave them good tidings that a Messiah was to come from God who would save them from dishonor and disgrace. So, they were awaiting a Messiah who according to their thinking was to be a king, who was to fight wars, conquering countries, gathering Israelites from all over the world, and bringing them within Palestine, establishing a very great, strong and powerful kingdom of the Jews.
Against their expectations, Prophet Jesus, son of Mary, came from God; they did not accept him as Messiah as he was not a king, he did not establish any kingdom neither strong nor weak so they refuted his claim and tried to kill him.
Thenceforth, all the Jews in the world are awaiting the expected Messiah, hoping that he would be a martial and political leader who will establish a Jewish Kingdom from Nile to Euphrates and will collect all the Jews in that land which they believe is theirs by inheritance.