From Chabad @
http://www.chabad.org/library/article_cdo/aid/108400/jewish/What-is-the-Jewish-Belief-About-Moshiach.htm
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Where is Mashiach mentioned in the Scriptures?The Scriptures are replete with messianic quotes. In Deuteronomy 30:1 Moshe prophesies that, after the Jews have been scattered to the four corners of the earth, there will come a time when they will repent and return to Israel where they will fulfil all the commandments of the Torah. The gentile prophet Bilam prophesies that this return will be lead by Mashiach (see Numbers 24:17-20). Jacob refers to Mashiach by the name Shilo (Genesis 49:10).
The prophets Isaiah, Jeremiah, Ezekiel, Amos, Joel and Hosea all refer to the messianic era. For full references the reader is referred to the book Mashiach by Rabbi Dr.I.Schochet. It is interesting to note that on the wall of the United Nations building in New York is inscribed the quote from Isaiah (Ch.11:6), “And the wolf shall lie with the lamb”. Furthermore, it is clear from the prophets, when studied in their original Hebrew, that Mashiach is a Jewish concept and will entail return to Torah law, firmly ruling out any “other” messianic belief.
What sort of leader will Mashiach be?Mashiach will be a man who possesses extraordinary qualities. He will be proficient in both the written and oral Torah traditions. He will incessantly campaign for Torah observance among Jews and observance of the Seven Universal Noahide Laws by non-Jews. He will be scrupulously observant and encourage the highest standards from others. He will defend religious principles and repair breaches in their observance. Above all, Mashiach will be heralded as a true Jewish King, a person who leads the way in the service of G–d, totally humble yet enormously inspiring.
When will Mashiach come?Jews anticipate the arrival of Mashiach everyday. Our prayers are full of requests to G–d to usher in the messianic era. Even at the gates of the gas chambers many Jews sang, “Ani Maamin” – I believe in the coming of Mashiach!
However, the Talmud states that there is a predestined time when Mashiach will come. If we are meritorious he may come even before that predestined time. This “end of time” remains a mystery, yet the Talmud states that it will be before the Hebrew year 6000. (The Hebrew year at the date of this publication is 5763.)
This does not rule out the possibility of Mashiach coming today and now if we merit it. It should be noted that many Torah authorities are of the opinion that we are in the “epoch of the Mashiach” and the Lubavitcher Rebbe stated on numerous occasions that the messianic redemption is imminent.
Could Mashiach come at any time in any generation?Yes. In every generation there is a person who potentially could be the Mashiach. When G–d decides the time has arrived, He will bestow upon that individual the necessary powers for him to precipitate that redemption.
Any potential Mashiach must be a direct descendant of King David as well as erudite in Torah learning. It should be noted that many people living today can trace their lineage back to King David. The Chief Rabbi of Prague in the 16th Century, Rabbi Yehuda Loew (the Maharal), had a family tree that traced him back to the Davidic dynasty. Consequently, any direct descendant of the Maharal is of Davidic descent.
Maimonides, a great Jewish philosopher and codifier of the 12th Century, rules that if we recognise a human being who possesses the superlative qualities ascribed to Mashiach we may presume that he is the potential Mashiach. If this individual actually succeeds in rebuilding the Temple and gathering in the exiles then he is the Mashiach.
What exactly will happen when Mashiach comes?Maimonides states in his Mishnah Torah – a compendium of the entire halachic tradition – that Mashiach will first rebuild the Temple and then gather in the exiles. Jerusalem and the Temple will be the focus of Divine worship and “From Zion shall go forth Torah, and the word of the L–rd from Jerusalem.”
The Sanhedrin – a supreme Jewish law court of 71 sages – will be established and will decide on all matters of law. At this time all Jews will return to full Torah observance and practice. It should be noted that in this present age of great assimilation and emancipation an unprecedented return of Jews to true Torah values has taken place. This “Baal Teshuvah” phenomenon is on the increase and paves the way for a full return in the messianic era.
Will miracles happen?The Talmud discusses this question and again arrives at the conclusion that, if we are meritorious, the messianic redemption will be accompanied by miracles. However, the realisation of the messianic dream, even if it takes place naturally, will be the greatest miracle.
According to some traditions G–d Himself will rebuild the third Temple. According to others it will be rebuilt by Mashiach, while others suggest a combination of the two opinions. Some suggest that there will be two distinct periods in the messianic era: the first, a non-miraculous period, leading on to a second miraculous period.
Maimonides writes, “Neither the order of the occurrence of these events nor their precise detail is among the fundamental principles of the faith … one should wait and believe in the general conception of the matter.”
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