When the spies returned from Eretz Canaan, they described the land in less than glowing terms. "We arrived in the land . . . and indeed it flows with milk and honey . . . however, the natives are mighty, the cities are fortified . . . the land devours its inhabitants and all those who reside there are giants" (Bamidbar 13, 27-32). Being that they wanted to paint a dismal picture, for what reason did they preface their tirade with, "indeed it flows with milk and honey?" Rashi explains that a falsehood which does not contain at least a minimal amount of truth cannot endure. Therefore, the spies purposely mentioned something true about the Promised Land, so that the rest of their lies would be believed.
Rav Wolbe (Shiurei Chumash) adds, Chazal say that sheker does not have the ability to stand. Because sheker is not a reality, it cannot become a reality. It might take ten, twenty, or even thirty years before the lie is proven false, but eventually the truth will become clear. Sheker's only chance of survival is if it props itself up with a truth.
Hence, the various ideologies that have surfaced throughout the world are all based upon some aspect of truth. For example, communism was founded to ensure social justice; a truthful concept. However, we are all witness to the terrible oppressiveness and deceit that were the hallmark of communism in Russia and other countries. The sheker feeds off of the truth on which it was founded.
Chazal tell us that Moshiach will arrive in a generation that is either completely righteous or completely wicked. We can understand why a completely righteous generation should merit Moshiach, but why would Moshiach reveal himself to a generation which is full of deceit? Rav Yeruchom Levovitz explains that in a generation which there is not even an iota of truth, the skeker will automatically be proven false and eradicated, thereby heralding Moshiach's arrival.
To a certain extent this concept has become a reality in our days. In the past few generations there has been a large increase in the amount of Jewish People that have found their way back to their roots; a veritable "Teshuva Movement." The falseness that abounds today is almost palpable, and at a certain point it simply exposes itself, and underneath, people have found the truth shining in all its brilliance.
The Torah is what gives the Jewish People their immortality, because it is the very word of Hashem - the eternal truth.