I have learned much from Michael Heiser, especially from his book, The Unseen Realm. Sadly, he passed away on February 20, 2023. Prior to his entrance into glory, I wrote him an email in which I challenged his view on the origin of the demonic hosts

As many of you know from reading his books, Heiser points to the fact that a wide range of Second Temple Jewish texts (i.e., extra-biblical, non-inspired documents, especially 1 Enoch and Jubilees) argue that demons are the disembodied spirits of the Nephilim.

“Specifically, the disembodied spirits released at the death of the giants [i.e., the Nephilim], the offspring of the union of the sons of God and mortal women, are the demons known in Second Temple texts and the New Testament Gospels” (112, n. 4).

Although this is certainly a possibility, it does raise several questions.

First, it is nowhere stated in the inspired biblical books of the OT. It is derived entirely from apocryphal texts of the Second Temple period. I am reluctant to build a doctrine in the absence of any explicit biblical text that teaches it.

Second, it does not appear that this would account for the plethora of demons that we read about in the NT. Recall that in the case of the Gadarene demoniac, a “legion” of demons indwelt him; i.e., 6,000; those demons in turn entered into more than 2,000 pigs. Were there really that many of the Nephilim that their disembodied spirits could constitute the totality of demons in the world?

Third, let’s not forget that the demonic hordes described in Revelation 9:13-19 numbered “twice ten thousand times ten thousand” (i.e., 200,000,000). Of course, this may be a highly figurative and exaggerated number, but it does suggest a massive demonic army. If the only demons that exist are the disembodied spirits of dead Nephilim and their giant-clan descendants, where did these 200,000,000 demons come from?

Fourth, why would not “the sons of God” who sinned so grievously in Genesis 6 themselves be demons? The fact that they are not so named in the OT does not negate the fact that they are spirit beings in rebellion against God. If so, the disembodied spirits of the Nephilim can’t be the first demons, as if none existed before the episode of Genesis 6.

Fifth, it is also hard to believe that the spirit-being who would later be given the name “Satan” was the lone rebel from among God’s divine council for some two thousand years of human history. In other words, Heiser’s thesis would mean that from the appearance of the “serpent” in the Garden to the time of the flood (some two thousand years?) there was only one “fallen” spirit-being (or angel). Whereas I grant that no biblical text explicitly states when numerous others from the divine council rebelled against God, it strains credulity to believe that the first “demons” did not appear until so long a time after the first one fell.

Sixth, I have one final concern. What is the nature of the “spirits” of the Nephilim? Are they not the spirits that exist as a result of the merger of fallen sons of God and human beings? So, would we not then conclude that “demons” are in some sense equally human as well as divine?

These concerns do not disprove Heiser’s thesis, but they are questions relevant to the case.