It depends on how seriously you take it.  If you take everything the bible says with an open mind and a perception of possibilities then it can be a nice thing to believe in a higher power, at an atheist would say like believing in fairy tales.

However if you are a devout mindless sheep who will take the bible to the grave and assault others beliefs in "gods name" then you both limit your own perceptions and subsequently your quality of life will deteriorate.  And worse you could even be hurting others with your doctrine.

Its poison only if you try to force others to believe it.