We really know very little about the spirit world, and it is probably just as well. Unfortunately, a lot that we think we know about is nothing but myth and guesswork. The entire question has been obscured by everything from ghost stories to movies, television, and even video games.
As far as I can tell, the only reliable source of information about this world is the Bible. And part of the problem, even in the Bible, is the ambiguity of the word
In both Hebrew and Greek, the words are quite similar in usage to the English word
spirit. Except that in Hebrew and Greek, the basic meaning of the word is
wind. Of special interest is the German word for spirit: geist, from which we get the word
ghost. Hence the King James translators (who were a lot closer to the old German than we are) could speak of the
Holy Ghost as opposed to evil spirits or ghosts. This gets lost in the translation, but the gospel writers speak of two kinds of spirit—one of them holy and one of them evil (or unclean, depending on usage). And it is plainly a deliberate contrast on their part.
We made the point in an earlier program that the word for
evil in Hebrew actually means
opposed. This may mean no more than a general attitude of opposition. But later, we encounter an incident where the spirit is very specific in that it comes and goes—almost personal. It is the first instance we discover in the Bible of a particular adverse spirit, and it is found in the history of the first King of Israel. His name was Saul.