The part with the neighbors was more or less only a joke. If i believe anything about them, then that they are good, honest and peacefull people. Because so far nothing happend to make be think otherwise.
The belief that the neighbors will kill someone (oneself for example) sounds more like a delusion... or a really bad neighborhood!
In both cases is a counter belief maybe not the best solution
But yes, i do think that beliefs can be helpful to counter inner urges and impulses. The belief in laws and punishment by law is an example for it.
And shared beliefs (for example faith and religion) acts like a glue for societies. The belief in eternal judgment by an all knowing god in combination with a holy law book (that is what most holy texts in their core are IMHO) helps to prevent chaos and ensures that people can work against a common and shared goal. As an example for the good and positive side of that.
The landscape should have some strong pillars and mountains of hard facts and factual truth. But besides that, yes it sounds like a good mind construct. Interesting idea for sure.