Do you believe in ghosts ? C.S.Lewis said he only met one woman who had ever seen a ghost and she said afterwards she didn't believe. It illustrates that perceiving is not believing. This article tells us that sightings of ghosts, demons, werewolves, black beasts and monsters of all kinds are higher than ever in modern day Britain.
A 'ghost' might be any number of things. It could be the unquiet spirit of a dead person who is still roaming this physical world. If this is so it is theorized that this might be because the person was too attached to this physical world and can't let it go. Others think that there is no objective reality to the ghost. In other words, it's not really a departed soul, but a kind of psychic 'memory' of the departed person which is imprinted on a particular place--maybe through a violent or unprepared death.
However, demonic temptation, oppression, obsession, infestation and possession are real enough and are a much more objective phenomenon than the other paranormal experiences. Many of them have more to do with disturbed psyche and peculiar realms of perception than anything objective.
Source: Standing On My Head
Oxford educated Fr. Dwight Longenecker is an American who has spent most of his life living and working in England. He was eventually ordained as an Anglican priest and served as a curate, a school chaplain in Cambridge and a country parson. In 1995 Fr. Dwight and his family were received into the Catholic Church. He spent the next ten years working as a freelance Catholic writer, contributing to over twenty-five magazines, papers and journals in Britain, Ireland and the USA. In December 2006 he was ordained as a Catholic priest under the special pastoral provision for married former Anglican clergy.