It is a narrowing of focus that is essentially the problem when examining any belief. In order to gain an expansive perspective and thus understanding of beliefs, an open mind must be maintained and new probabilities entertained in order for them to be of value.
You create your own reality. When you focus on a desire or a belief the Universe/All That Is will respond with every probable variation thereof presenting you with the opportunity to experience it in every aspect. From the vantage point of your current focus you will then choose to experience the aspects that are most relevant to you at any given moment, of that belief/desire/expectation. If you have any doubts regarding the nature of your belief, they too will be manifested as objections, and challenges, enabling you to evaluate its validity for you.
Emotional intent behind any thought must be clear and well focussed for it to become a physical reality that you might then perceive as having any solidity or sense of permanence. All thoughts are manifested, even though many may fall outside of your perceivable framework of reality.