Genesis contains a very curious passage: When men began to multiply on the face of the ground, and daughters were born to them, the sons of God saw that the daughters of men were fair; and they took to wife such of them as they chose. Then the LORD said, “My spirit shall not abide in man for ever, for he is flesh, but his days shall be a hundred and twenty years.” The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of men, and they bore children to them. These were the mighty men that were of old, the men of renown (Gn 6:1-4).

Some Fathers of the Church, including St Clement of Alexandria, interpret the “sons of God” as “the angels who forsook the beauty of God for perishable beauty and fell as far as heaven is from the earth.” By this interpretation, some fallen or falling angels had sexual intercourse with women, resulting in a race of giants known as “Nephilim.” Other Fathers, including St Augustine, read “sons of God” as human beings who descended from the line of Seth, rather than from the line of wicked Cain.

In his book Angels (and Demons) (q. 58, pp. 91-92), Peter Kreeft follows the tradition represented by Clement – whether wittingly or unwittingly – by interpreting the Nephilim as the children of giants who copulated with fallen angels. Although his book is exemplary in many ways, Kreeft omits the fact that there is no consensus among the Fathers of the Church on this point.

Consider, for example, the following passage from St Ephrem the Syrian. Moses (that is, the author of Genesis), according to Ephrem, “called the sons of Seth ‘sons of God,’ the righteous people of God. The beautiful daughters of men whom they saw were the daughters of Cain who adorned themselves and became a snare to eyes of the sons of Seth. Then Moses said, ‘they took to wife such of them as they chose,’ because when ‘they took’ them, they acted very haughtily over those whom they chose. A poor one would exalt himself over the wife of a rich man, and an old man would sin with one who was young. The ugliest of all would act arrogantly over the most beautiful.”

St Augustine follows a similar line of interpretation, by reading the “sons of God” in Genesis 6:1 as good men who became corrupt in Genesis 6:2. His interpretation is, in my mind, the best ever given of the passage. It appears in the City of God (XV.23).

Augustine notes first of all that people of large stature are still around; just visit a circus and you are likely to find one, or think of wrestler Andre the Giant. Some simply translate “Nephilim” as “giants.” That there were many giants around in the ancient days discussed in Genesis 6:1-4 is entirely possible, and does not demand any supernatural explanation.

Augustine next notes that the accepted text of Genesis 6:2 does not speak of “angels,” but rather of the “sons of God.” According to Kreeft, “sons of God” is a generic term for heavenly beings. It is also, however, a generic term for human beings who live in God’s grace. We are sons and daughters of God by grace or adoption.

So Augustine interprets the passage as follows. The “sons of God” – those who loved God and sought him above all things – became enamored with the beauty of women, and the seductions of other worldly things. This led them to fall from the love and grace of God into the mire of the constant pursuit of worldly pleasures and accomplishments. Once all God-fearing, just men have disappeared from the earth (except Noah), the flood comes (the topic of Genesis 6:6 and following).

Augustine is aware that the book of Enoch teaches that the Nephilim were the offspring of mating between angels and men. It is likely, in fact, that Clement of Alexandria followed Enoch on this point. Augustine, however, appropriately notes that the book of Enoch is apocryphal, coming from uncertain and untrustworthy origins, and is left out of the canon of Scripture for good reasons. Beware what you read on the internet: anyone who takes the Book of Enoch as an authority on Nephilim, angels, or anything else is not thinking with the mind of the Church.

In summary, Augustine’s interpretation of the passage regarding the Nephilim in Genesis 6:1-4 is sound and convincing, and any who are further interested in the topic should read it. Quite simply, the passage is not about fallen angels mating with men, which is an ontological impossibility. A horse cannot be the biological father of a cricket; it is even less possible for a demon (a pure spirit) to be the biological father of a man (a creature both physical and spiritual).

St Thomas Aquinas, the Angelic Doctor, also follows Augustine on this point. Aquinas address it in his Summa theologiae I, q. 51, art. 3, rep. 6: “As Augustine says (De Civ. Dei xv): ‘Many persons affirm that they have had the experience, or have heard from such as have experienced it, that the Satyrs and Fauns, whom the common folk call incubi, have often presented themselves before women, and have sought and procured intercourse with them. Hence it is folly to deny it. But God’s holy angels could not fall in such fashion before the deluge. Hence by the sons of God are to be understood the sons of Seth, who were good; while by the daughters of men the Scripture designates those who sprang from the race of Cain. Nor is it to be wondered at that giants should be born of them; for they were not all giants, albeit there were many more before than after the deluge.’ Still if some are occasionally begotten from demons, it is not from the seed of such demons, nor from their assumed bodies, but from the seed of men taken for the purpose; as when the demon assumes first the form of a woman, and afterwards of a man; just as they take the seed of other things for other generating purposes, as Augustine says (De Trin. ii.), so that the person born is not the child of a demon, but of a man.”

Note the incubi in the above passage, which are equated with satyrs or fauns, and assumed to be demons or fallen angels. Incubi were thought to be demons who had sexual relations with women, sometimes producing a child by the woman. Succubi, by contrast, were demons thought to have intercourse with men. Superstitious folk have for many centuries told salacious tales of incubi and succubi, and Genesis 6 is a passage used to support the credibility of such stories. These terms remain current among heavy metal bands and occult groups today. Yet the existence of incubi and succubi cannot be claimed as part of Catholic teaching or sound Tradition.

In the passage cited above, St Thomas Aquinas neither affirms nor denies the existence of incubi. He merely insists that, in theory, any child born of such a union could not be half-demon and half-human: only human seed can produce a human offspring. Thus any human being in the world is fully human. Therefore one should not guess at the supposed ‘demonic’ biological origins of a man, despite his behavior or appearance. In this manner, Aquinas protects the dignity of all human beings from a potentially dangerous superstition.

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