Mashiach means "anointed one". In the Hebrew Bible it is a title, not a role in the future: kings and priests are anointed with oil and are therefore the LORD's anointed, and the word is applied to reigning kings of Israel and, strikingly, to the Persian king Cyrus (Isaiah 45:1), who was not an Israelite at all. Only in the Second Temple period does the term come to denote an awaited deliverer, and even then the expectation was never single. The Dead Sea Scrolls attest a hope for two messiahs, one of Aaron and one of Israel; other texts look for a prophet like Moses, or for a heavenly figure like Daniel's one like a son of man, and a great deal of Second Temple literature has no messianic figure at all.
Jewish expectation, as it settled in rabbinic tradition, is for a human descendant of David who will gather the exiles, rebuild the Temple, restore the observance of Torah, and bring an age of universal peace and knowledge of God. Maimonides sets out the criteria in the Mishneh Torah and makes them deliberately public and verifiable: if a claimant accomplishes these things, he is the messiah; if he does not, he is not. The consequence is that Judaism has never accepted a claimant, and that the false-messiah episodes, Bar Kokhba in 132-135, and above all Shabbetai Zevi, whose mass movement in 1665-66 collapsed when he converted to Islam under Ottoman pressure, are read as confirming the criteria rather than as exceptions to them. Rabbinic sources also caution repeatedly against calculating the date of the end.
Christianity holds that Jesus is the messiah, Christos is simply the Greek translation, and reinterprets the office around his death and resurrection, drawing on the suffering servant of Isaiah 53 and the son of man of Daniel 7, and deferring the visible restoration of the world to a second coming. Jewish objections have been consistent since antiquity: that the messianic conditions plainly were not met, that the proof texts are read out of their contexts, and that the further claim of incarnation is a separate and greater difficulty. The medieval disputations at Paris in 1240, Barcelona in 1263 and Tortosa in 1413-14 were public stagings of this argument, conducted under conditions of severe coercion in which the Jewish participants could not safely win.
Islam accepts Jesus as al-Masih, using the title of him repeatedly, while denying his divinity and, on the standard reading of 4:157, his crucifixion, and holding that he will return before the end. Sunni Islam attaches its own eschatological expectation chiefly to the Mahdi, a figure not yet born. Twelver Shia Islam identifies the awaited deliverer with the twelfth Imam, held to have been born in the ninth century and to be in occultation, whose return alongside Jesus will fill the earth with justice.
The expectation continues to generate live disputes. Within Chabad Hasidism a substantial number of followers regarded the last Rebbe, Menachem Mendel Schneerson, as the messiah before and after his death in 1994; the position is held with varying degrees of explicitness and has been strongly criticised by other Orthodox authorities as incompatible with the tradition's own criteria.