I've been reading Carl Sagan's book, The Demon-Haunted World. He has been talking about belief in demons and witches through the ages, pointing out that most everyone believed in these kinds of things through most of history. People have often believed they have had interaction with demons, spirits, and gods. They have sometimes believed that spirits have had sexual relations with women and men, and even produced children by such relations. Sagan is arguing that, now, we have naturalistic explanations that explain these sorts of phenomena. People are capable of hallucinating and dreaming, and it is interesting that many of these phenomena have occurred when people are close to sleep, have been alone for a long time, etc. Today, interaction with spirits has been joined by interaction with aliens, and the patterns of interaction are very similar. This is not surprising, as people today, living in a more naturalistic, science-oriented world, have the opportunity to gravitate towards the "scientific" equivalents of supernatural beings--namely, advanced extraterrestrials. Therefore, Sagan argues, a scientific, skeptical attitude would have us leave off the old supernatural explanations that almost everyone used to believe, and go with naturalistic explanations.
I think there is much merit to what Sagan has to say. But I think he may be jumping to conclusions in a similar way to the way many have through history, but in a different direction. In the past, people jumped to supernatural explanations. Sagan's tendency seems to be to jump to naturalistic explanations. He is quite right to point out the likely fictional nature of much of the supposed experiences people have had with the supernatural (and with naturalistic aliens). But pointing out false experiences is not the same as showing that all experiences are false. Consider this scenario: People really have had interactions with supernatural beings in history. Some people have had encounters with God. Some have interacted with angels and/or demons. The Bible tells of supernatural encounters--though, interestingly, there seem to be times when such things happen more often than at other times. In the Old Testament, there is very little interaction, overall, with supernatural beings such as angels and demons. Angels do appear, but only rarely. There are very few encounters with evil spirits. Of course, there is much interaction between God and a few people, known as prophets. In the Gospels, there is an explosion of demonic activity, which again dies down to a significantly lesser degree in the Book of Acts. Perhaps one reason for the increased demonic activity in the Gospels is that Jesus, the Son of God, is on the earth. It is a time of increased supernatural activity. Satan knows his time is short. There is a strong and visible exhibition of the ongoing war between good and evil. God has often, according to the Bible, spoken to people through dreams, visions, etc. Such visions are associated with going out into the desert, being alone, sleeping, etc.--sometimes. Sometimes not. Sometimes miracles are in broad daylight, with lots of people around, in non-hallucinatory conditions. Perhaps God designed odd states of consciousness partly as a vehicle for occasional communication, while at other times those states are left to wander randomly through the mind's experiences and imaginations. (And we are asked by the Bible to "test the spirits," and not be gullible.) However, even though there really have been supernatural encounters, even at times where there were not such encounters people have dreamed them up, often in imitation, perhaps, of the real thing. At the basis of many myths is some real event or person, exaggerated by men's imaginations. The same thing seems likely here. According to the best reading of the Bible, revelation has ceased at the end of the apostolic age, in the first century. Satan has been bound, and the gospel has gone out to all the world. Miracles (of the good sort) seem to be associated with revelation, so we would expect a ceasing of such miracles after the apostolic age. Since Satan has been bound (as well as since Jesus is no longer on the earth), we might expect a ceasing or at least a diminishing of demonic activity as well after the first century. (It is possible that such ceasing of demonic activity might have been all at once, or perhaps it has been gradual, as the gospel has gone out to various nations.)
If such a scenario as I have described above is true, it would explain the phenomena Sagan observes at least as well as his own naturalistic account. Sagan is right to point out much superstition in people's thinking and experiences, but he is jumping to conclusions when he reasons from that to the non-existence of supernatural encounters. A biblical picture of the activities that have gone on and that go on in the world seems to me to explain the data at least as well as Sagan's naturalistic view; but he doesn't consider that, perhaps because he has already concluded on other grounds that naturalism is true. Skepticism needs to be applied not just to supernatural explanations, but also to naturalistic ones. We need to avoid jumping to any conclusions, but instead to try to apportion our beliefs as precisely as possible to the actual state of our known evidence. It may be hard to prove which one is right--the biblical view or Sagan's view--on the evidence of the anecdotal data alone. But since I have other reasons that lead me to be convinced that the Bible is the Word of God, I justly favor the biblical explanation.