The argument is in LM I:15: One must bring fear up to its root. Because when does not do so then fear is dressed in everything in this world.
The idea is that when there is judgment below there is no judgment above. So when one judges himself on everything he does then there are no judgment upon him above. But when one does not judge himself then they do judge him in heaven and then the judgments are dressed in everything  this world. and when the judgment are dressed in things in this world then he has fears. he is afraid of things because they in fact have the power to hurt him since the higher judgments are dressed in them.



Just as a side not I should mention that there are too many religious groups out there that cash in on the appearance of authenticity. And I admit it would be nice to have a gauge to measure such a thing.
My suggestion for authenticity in Torah would be to find a decent Litvak yeshiva and also go to Israel. Preferably both together. And if you want the authentic Israeli experience I recommend going into the IDF. In fact in the context of Musar there is a certain amount of opinions that are not well to my liking. The amount of people that think being against Israel is a good thing is astonishing. I am not impressed with their arguments.