"Belief is a beautiful armor but makes for the heaviest sword." - John Mayer
I was raised to believe that a talking snake convinced a woman to eat a fruit that was forbidden in a garden called Eden, at the beginning of creation. Along with other fantastical stories I learned that a donkey spoke, a virgin gave birth, and a perfect man once upon a time turned water into wine. Since I once believed these wonderful stories told to me as a child, Italo Calvino's story of Adelma, from his book Invisible Cities was just another walk in the park.
The story of Adelma is an example of how belief can be useful as a coping skill. We observe that this is the case for the weary traveler, Marco Polo and the ailing emperor Kublai Khan alike. The former, whether he believes his adventure to be a dream or not, seeks to justify his story by coming to terms with his own mortality. The latter, uses belief as a comfort to mask reality from his deathbed.
Some may argue successfully that belief by itself is harmless. However, when belief without evidence is utilized as a weapon, we are all too familiar with the testament of how deadly a force it can become. World wars have been raised and have raged since the beginning of time, in the name of infinitely disparate beliefs.
Before you take the next person's word as gospel, I implore you to be a tad more skeptical. Take instead, the liberty of thinking for yourself. It could mean the difference between life and death.