The Tanach lays the prophetic foundation for Mashiach's reign: Yeshayahu 11:4 portrays him judging the poor with righteousness and striking the wicked by the breath of his lips, Yechezkel 37:22 foretells that God will make Israel one nation under one king, and Daniel 7:14 declares that dominion, glory, and kingship will be given to him — an everlasting sovereignty that will not pass away.
The Gemara in Pesachim 54a records that the name of Mashiach was among the seven things created before the world itself, establishing that redemption through him is woven into the very fabric of creation, a point that the Tanya (Likkutei Amarim 36) develops by teaching that the Messianic Era, and especially the Resurrection of the Dead, is the fulfillment and culmination for which the world was originally made.
Berakhot 34b teaches in the name of Rabbi Yochanan that all the prophets prophesied only concerning the days of Mashiach, while the World to Come remains beyond the eye's sight — grounding the entire prophetic corpus in Messianic expectation — and the Or HaChaim (Bamidbar 24:17) adds that the timing of redemption is contingent: if Israel merits it, God will hasten it; if not, it will come in its fixed time.
The Gemara in Sanhedrin 97a–99a records a foundational dispute about whether repentance is the prerequisite for redemption — Rav holds all appointed times have passed and only repentance and good deeds remain, while Rabbi Yehoshua counters that if Israel does not repent God will raise up a harsh king to bring them back — and Sukkah 52a adds that the Sages themselves disagreed whether the end-times eulogy is for Mashiach ben Yosef who falls in battle or for the evil inclination that is ultimately slain.
The obligation to believe in Mashiach's coming is grounded in Devarim's command to heed the prophet (Devarim 18:15–18), and the Sefer HaIkkarim (Maamar 4:42) rules that since the prophets foretold the coming of Mashiach, whoever does not believe in it denies the prophets and transgresses a positive commandment — though he carefully distinguishes this from a foundational dogma whose denial makes one an outright heretic, a position he develops in Sefer HaIkkarim (Maamar 1:23), where he describes belief in Mashiach as a branch growing from the root of reward and punishment, an accepted belief incumbent on every adherent of Moshe's Torah, but not itself a root without which the Torah would collapse.
The Rambam (Hilkhot Melakhim 11:1) is even more stringent, ruling that whoever does not believe in Mashiach or does not await his coming denies not only the other prophets but the Torah and Moshe our teacher himself, while Hilkhot Melakhim 12:2 instructs that one must not calculate the end-times and must simply wait and believe in the matter in general, in keeping with what he explained — and Sefer HaMitzvot, Positive Commandment 3 ties this to the commandment of loving God, which includes calling all people to belief and knowledge of the truth.
The Chatam Sofer (Yoreh De'ah 356) rules that Rabbi Hillel's view in Sanhedrin 99a — that there is no Mashiach for Israel — has been rejected by the majority of Israel's Sages, and therefore one who follows that view today is considered as one who denies the foundations of the Torah, since the rule of following the majority applies; Responsa Benei Banim (vol. IV, 26) addresses a related boundary question, ruling that those who mistakenly identify a deceased figure as Mashiach — even expecting him to return — are misguided but not heretics, and their shechitah may be relied upon if they are otherwise observant; and Responsa Benei Banim (vol. III, Essays 3) argues that the Rambam himself did not require belief that Mashiach is coming at any specific moment, only that one wait and believe in his coming in general.
Igros Moshe (OC 5:8) addresses the obligation to anticipate the coming of Mashiach each day and concludes, on our reading of the cited page, that one must expect Mashiach with certainty at any moment, and this expectation is the basis for various halachic stringencies relating to Temple service and offerings even under current conditions of ritual impurity.
Adir Bamarom (Beur Idra Rabba 7b) teaches that Mashiach is destined to bear the sufferings and restraints of the forces of impurity on behalf of Israel, and that wherever those forces become attached during their ascent they remain trapped, like a bird in a snare — linking Mashiach's role to the cosmic suppression of evil — while Sefat Emet (Rosh HaShanah 5651) teaches that by praying wholeheartedly for God's kingship to be established over all, Israel first merits the kingdom of Heaven, connecting Messianic longing to the daily acceptance of divine sovereignty; and Maamarim Melukatim (Acharon shel Pesach 5749) concludes, on our reading of the cited page, that every Jew possesses the power to move immediately from the commemoration of the past Shemot to the revelation of the future redemption without any delay.