Rabbi Immanuel Schochet is quoted here as saying:
The Rebbe revived the fundamental principle of Judaism — to believe in the imminent coming of Moshiach — which had come into complete neglect. People basically ignored it... Before the Rebbe, who discussed the principle of Moshiach as a vital reality?While Rabbi Schochet is much older than I, everything I know about this contradicts his claim. In fact, his statement is extremely outrageous to the point of offensiveness. I don't know if he fully recognizes what he is accusing the world of being before the Lubavitcher Rebbe. I don't know if he understands who he charging with near-heresy or, at best, spiritual sleep.
The worst thing is that even if Rabbi Schochet recognizes that he is merely making an exaggerated statement, there are plenty of people who read/hear things like that and believe it literally. They honestly think that the vast majority of frum Jews did not truly believe in a fundamental principle until the Lubavitcher Rebbe came onto the scene.