A well-researched and organized, pointed study, "Essentials of Demonology" still manages to be unsatisfying somehow. Langton clearly and carefully has read the key ANE and Greek sources here: the Arabic, Babylonian, Assyrian, and Persians myths; the Old Testament and Apocryphal/Pseudepigraphal writings; and the Gospels and the letters of the New Testament. He is also a seasoned scholar, passing over unnecessary information and rarely allowing himself to become sidetracked. But, Langton brings to this study a kind of modern, critical attitude mixed with a severe dismissal of virtually all ancient ("primitive") mythic and metaphysical systems. Briefly stated, Langton does not believe in the existence of evil spirits, demons, and devils. He things all of these beings are figments of primitive imagination. The New Testament simply reflects the primitive imagination of the times, the one it inherited from Jewish apocalypticists. However, Langton fails to integrate his skepticism with his Christian confession and so the study ends up being a well-researched, though schizophrenic, categorizing of ancient views on demons with some poorly argued, reductionist conclusions. These conclusions basically amount to him saying Jesus Himself shared the ANE's primitive conceptions, and all demonic possessions are caused by mental imbalances.
Indeed, this is the strangest and weakest part of the book. Langton cannot reconcile the fact that Jesus is an exorcist. He believed Himself to be one, the Gospel writers portrayed Him to be one, and the NT epistles reflect the same demonological ideas. Yet, if demons aren't real, then what was Jesus actually doing? Langton points out that some say that it was by the power of personality that Jesus drove out "demons" (which were actually mental problems). Others say that Jesus was just pretending, that He was stooping down to stupid, superstitious humanity, in His actual quest to save us from our sins. Langton adopts the (as one would expect) modernist view that Jesus was ignorant (according to His human nature), and so shared the assumptions of His countrymen.
There's no subtlety here; Langton is not arguing that the demons could be conceived of as "patterns" or "principles" of various evils, that they have bodies and existences according to humanity's participation in those patterns. He doesn't say that demons could be beings above and outside of our scientific knowing, that we therefore simply can't say much about them. No - he simply says that they can't possibly exist, and therefore the entire NT is rooted in ignorance. Langton argues that this ignorance does not change the essential focus of the Bible, that is, the salvation of mankind from sin and death. But let's be honest, if Jesus and the Apostles were this misguided, this ignorant - that a major emphasis which virtually underlies all of the New Testament - the triumph of Christ over Satan - is simply a made-up, primitive notion, what does that say about the truth of the Word of God itself? Why should people this primitive (to use Langton's phrase) be trusted when it comes to spiritual teachings? Why trust any of it at all? How can Langton believe in angels but not in demons? In the Body of Christ but not the body of Satan? Christians don't believe this stuff because it sounds measured and probable. None of it does! It's problematic and dangerous and impossible and exciting. But it just might be true... ! And in faith, we take the step of saying that it is true, that we don't understand fully, that Christ who overcame demons will forgive our deficiencies.
Other weaknesses of the book include the unfortunate tendency of the author to write things like "Clearly, this means," and "Obviously this shows," etc. This bugs me like nothing else. Let the data speak. Let the facts argue. Words that attempt to steer the reader in one direction often cover up weak argumentation and unclear formulations.
Langton rarely mentions the early Church except for a reference here and there to some Apostolic Fathers. This study is sorely lacking in early Christian demonological insight. I'm guessing the reason is that Langton was uncomfortable with the fact that every single Patristic witness confessed the same belief in the power of the Devil that Langton, in all his enlightened modernity, declined to accept. And, not only did the Church Fathers write about demons, accepting them as part of reality, but they saw them! They battled with them! Think of Antony, Macarius, Pachomius, and all those other enlightened heroes of the desert, those champions for Christ. Think of Clement, Origen, Athanasius and all the other philosopher-theologians of Alexandria. All these pious saints proclaim with one voice that Edward Langton is the ignorant one.
Where I found the study helpful was in the relation of Arabic and Babylonian/Assyrian demonology to the (hints) of demonology in the New Testament. At several places in the Psalms and Isaiah, there are brief and oblique references to demonic entities that were well-known and either feared or worshiped by the peoples which surrounded Israel. Likewise, Langton's explanation of Azazel, the desert-demon turned Satanic angel was immensely helpful. There were some interesting insights also into the Platonic view of demons, though the author admits that these views had little impact on the Jews and the milieu of the New Testament.
Overall, I wish this was a more balanced book. In its surveys of ANE views, it's well-done. In its summary conclusions on Christ's views, it's almost nonsensical. For classic studies on demonology, I much prefer the 1951 book "Satan," written by a team of French academics and monks who actually had met Satan and the demons and knew their workings quite well, because they lived faithfully as believers in the time of Hitler and the Holocaust.