An unprecedented level of excitement has been generated in the aftermath of the announcement by the Lubavitcher Rebbe, Rabbi Menachem M. Schneerson, Shlita, that the Time of the Redemption has arrived. People are especially intrigued at the idea of pointing to a human leader in our times as the Moshiach. Jewish tradition provides clear sources for this view.
Rabbi Moshe Sofer (Chasam Sofer, Responsa 6:98) writes that "In every generation, there is one tzadik who has the potential to be the redeemer." Since one must expect Moshiach's arrival every day (Talmud, Eiruvin 43b) there must always be someone who is designated to assume this responsibility.
The Talmud (Sanhedrin 98b) relates how R. Yehuda HaNassi and other Talmudic sages throughout history were identified by their disciples as the potential Moshiach of their generation. Indeed, the great Sephardic encyclopedist, R. Chaim Chizkiyahu Medini states in his work, Sdei Chemed (P'at Hasadeh kelalim s.v. aleph:70), "In every generation they assessed who this person was."
The Rambam delineates the qualifications of Moshiach. "A descendant of King David, well-versed in Torah and occupied with the Mitzvot as stated in the written and oral law as was David his forefather. He will prevail upon the entire Jewish people to walk in (the) ways (of Torah). He will strengthen its breaches and fight the battle of G-d. "One who is engaged in all of the above, Maimonides concludes, "it is presumed that he is Moshiach."
Many prominent rabbinic authorities and Gedolei Yisroel have stated, verbally and in writing, their Jewish legal ruling (psak din) that the Lubavitcher Rebbe, Shlita has fulfilled the conditions described in the Rambam to be presumed with assurance to be the Moshiach.
Knowing the identity of Moshiach does not mean that the Redemption has already taken place. There are two distinct stages as detailed by the Sfas Emes (Rosh Hashana 11a) in comparing the future redemption to the exodus from Egypt. The Jews were still slaves even after Moses was chosen by G-d to be the redeemer. Similarly in the final redemption, first Moshiach is identified and the second stage will be when the redemption occurs. Moshiach then rebuilds the Holy Temple and takes all the Jews back to the Holy Land