If you are not dealing with all of reality you are not dealing with any of it. Many organizations in the past have tried to decide what people should believe in and what they should not believe in and otherwise attempt to control their lives, they all failed.
As Lily expressed in his books there is much in our belief systems that can be discarded as so much extraneous baggage. Contradistinctively we must not toss aside beliefs that are essential and propitious for our survival.