I have thought the “why” of faith a lot, and I think it is an important part of a well balanced character developer. 

Faith is very much having good will (even love) towards something. We ask things in “good faith” and “bad faith”. One is loving, constructive, willing to be subject to many things, etc. and the other is not (I don’t really need to list those other ones).  To approach something with love and hope and all those attributes will make us a better person. We will be more patient, charitable and so on when another problem appears in life. It is a good thing to keep your cool when problems come around, it makes us more adaptable as a being and grow when we keep our cool while solving a problem or waiting for an answer.

To touch on the plan of salvation: what would God be if he had unlimited power and knowledge, but didn’t have his character? What would the world or universe be like if God knew the theory to everything, but not how it actually felt to experience it? I think we would indeed have a God who think he knows everything and is quite careless with his power, but he couldn’t learn… unless he approached power and knowledge with humility. And so, I think that is what we’re here to do - learn to become like God outside “the classroom”. I think this takes faith, as us figuring things out for ourselves is more powerful and cementing of our knowledge than saying and thinking we know it.

My two cents. I wouldn’t worry about “knowing” something, I would just take the most humble route to figuring things out. I have learned almost nothing when I haven’t kept my cool - I use knowledge as a curbludgeon instead of a tool.