Belief in God is rational.
Everything has a cause. So unless there is a first cause, then you would have an infinite regress. And then nothing could exist. Therefore there must be a first cause. Therefore God, the first cause, exists. QED. (You could prove the first step a priori that everything has a cause by noting that nothing can come from nothing. This makes it a priori, not just an empirical observation).
You find at the beginning of Rav Shick's pamphlets that they are "based on Reb Nachman's teachings and they are interspersed with statements from the Old Testament and the Sages." What is that supposed to mean is a mystery to me.
More than that. The whole religious world holds all kinds of practices that are supposedly based on Torah.
IF YOU CHALLENGE THEM TO PROVIDE SUPPORT they say "it's totally from the Torah! It's one hundred percent from the Torah!". This avoids the real problem, which is that the teaching is merely BASED ON THE TORAH, and not actually Torah.
What's the difference, I hear you ask. Well, have you ever watched a movie that is "based on the novel by...." whoever. And if you have read the novel, you find to your disappointment that the movie that is BASED upon it misses out a lot that is stated, and implies a whole lot more that isn't in the book. It's drawn from the book, it's based on it, but it's NOT the book! [I have a high opinion of Rav Shick in terms of sincerity. And as an approach to Reb Nachman, it is the only sane one out there. Still because of my respect for him I feel the right to critique him. I would not bother with him otherwise.]
The trouble seems to be השחתת המידות destruction of good character traits when one gets involved.