WHY WE NEED A REBBE?
There are those who ask, “Why is it necessary to have a Rebbe? Can’t one maintain his relationship with G-d independent of an intermediary?”
They concede that those unable to connect to G-d by themselves may need someone to help them achieve that connection, but shouldn’t a scholar be able to relate to G-d by himself?
They take their argument further, that while it was necessary that Moshe bring the Shechina down into this physical world before Mattan Torah, now after Mattan Torah, when Torah can be studied by everyone, why can’t one learn Torah and connect to G-d by himself?
The answer is that ever since Mattan Torah, it is necessary to have an intermediary like Moshe, as it is written (Voeschanan 5:5) “And I stand between you and G-d,” -- and this must be through a Rebbe. If not. . . our Sages tell us (Sanhedrin 110a) that whoever is “cholek” (contends) against his Rebbe is as if he is “cholek” against the Shechina (Divine Presence) [“cholek” in Hebrew also means to separate.] If one does not have a connection to his Rebbe, he not only separates himself from his Rebbe, he is then not only lacking a component, but he also separates himself from the Shechinah. So how can he have Torah without a Rebbe? Without a Rebbe one cannot connect to the Shechina.
And this is the same in every generation. There is a Moshe in every generation, and by connecting to him we connect to the Shechinah.
(Sichas Shabbos Parshas Shemini 5726)
