To those who haven't read Father Seraphim Rose's book, he was a serious student of the UFO phenomenon and his book has an excellent, informed discussion even though it was written in the early 70's. The book is also highly prescient in describing exactly the New Age direction modern religion is going. As I recall, he attributes the phenomenon to demonic forces, which is indeed one possibility that is given serious consideration within modern ufology. He was an American who lived a short but fascinating life, and this book has been extremely popular even in Russia. However, I took the original post here as positing the arrival of actual, non-demonic extraterrestrials.