The disbelief (IM 655)

Everyone has some sort of disbelief in something. Everyone, without exception has someone whom they find hard to believe in. Things can be true, but it's difficult to accept it and people can be trustworthy but we find them unconvincing. Everyone has some unique set of disbelief in something/someone... The important and most difficult question is: How to change our mind to believe in that/them? What criterion are we looking for believing? It's worth it to answer these questions.