In the previous Rebbe’s work Basi Leagani, he writes, that the Shechinah (a level of Hashem) originally dwelt in this world. But due to the sin of seven generations, it was removed seven levels to the seventh heaven.
The physical world is based, on cause and effect, with the effect being related to its cause. The effect, is also part of the cause. This is similar to the way nature works. Science has been able to figure out, the cause of many phenomena in our existence, based on the effects they see in the world.
But there exists another form of existence, that is outside the realm of cause and effect; it is called creating something from nothing. Here the effect, has no relationship whatsoever, to the cause.
This level comes from the level of, the Etzem of Hashem.
After these seven generations, there were seven Tzadikim, who brought the Scheina back into the world, level by level. But the last level, of bringing the Scheina from heaven to the earth, is the hardest jump to make.
Because this is not a jump of cause and effect, rather it is the level of “something from nothing”, an infinite jump. Only Moshe, who had a very high soul, could accomplish this.
But the sin of the golden calf, again sent the Scheina away from the earth.
When Jews sin, they push the Scheina, Hashem, away from the world, and hide Him. But when they go beyond limitations to do Mitzvahs, they reveal G-d in a very powerful way. This is because, they are directly connected to Hashem, by virtue of their souls.
When Jews hide G-d in their souls, by doing a sin; they also hide Him in the world at large, because man is called a microcosm, a small world.
So too now. The world has constantly gone through a process of refinement, from the time of Adam, until now. This refinement has now reached the point in our generation, where Jews can access the ultimate level of their souls: the “Moshiach level” of their soul, the highest level. This level is connected to the Etzem of Hashem.
The Moshe Rebbenu of our generation, is the only one able to bring down the Scheina into the world now, since he has the soul of Moshiach. But he needs us.
Through Jews screaming out to Hashem, that they want Moshiach now; and saying, that the Rebbe has to be revealed, etc. they cause Hashem to be revealed in the world- the Geula!