as your brain is refreshing itself during sleep there are periods of dreams. that your dreams in particular would have something to do with god is of no surprise. my dreams too often have to do with what i think about a lot, presented in some weird way. however i've found i only really remember them if it turns into a lucid dream -- a dream in which you know it's a dream. the rest all fall away. and in a lucid dream you are at least partially controlling the outcome.
but i wasn't asking about why you believe your own dreams, i was asking why you believe what someone else had in a dream. why is random guy on internet a good source and not, say, joseph smith who dreams about god telling him stuff