Any form of belief in the arbitrary is potentially dangerous in some way or another, if only in alienating oneself from reality. On principle, I don't believe in anything I don't know and understand, especially when everything I do know excludes the possibility by virtue of contradiction to what is real.
Since what we choose to belief influences subsequent choices and actions, often on a subconscious level, it behoves us to question the source and validity of anything and everything we believe. We are no less responsible for the beliefs we hold, whether by default of inheritance or by intention, than we are for the consequences of the actions that follow from them, not just our own but those of others whose beliefs we endorse as well.
Beliefs may be derived from make believe, but their consequences are no less real.