Augustine’s answer is that the “sons of God” in Genesis 6 were human beings, associated with the line of Seth, not angels who fathered the Nephilim. He reads their marriages to the “daughters of men” as the breakdown of a faithful community’s way of life. The giants, in his view, were remarkable but human people; their size did not require angelic parents.
That conclusion can be easy to miss if we read only Augustine’s earlier mention of the question. In The City of God, Book III, chapter 5, he raises the possibility of fallen angels and human women but leaves it open while making a different argument about Roman myths. His developed treatment comes later, in Book XV, chapters 22–23, where he explains why he favors a human reading. Read Book III in the 1871 translation; read Book XV in the companion volume.
For our own Scriptures suggest the very similar question, whether the fallen angels had sexual intercourse with the daughters of men, by which the earth was at that time filled with giants, that is, with enormously large and strong men.
Augustine, The City of God III.5 (text).
Why did Augustine call them human?
Augustine’s account starts with the two communities that run through The City of God: one oriented toward God and another toward earthly goods. In Book XV, chapter 22, he identifies the “sons of God” with the former community and the “daughters of men” with the latter. The men become captivated by beauty, adopt the ways of the other community, and abandon the conduct they had followed. For Augustine, the passage describes a moral and spiritual falling away among people, not a biological crossing between angels and humans.
He connects these communities with the descendants of Seth and Cain. In chapter 23 he explicitly describes the marriage as one between “the sons of Seth” and “the daughters of Cain.” This is Augustine’s interpretation of the Genesis narrative, not a family label stated outright in Genesis 6:1–4. The force of his reading comes from the surrounding genealogies and his larger contrast between the two cities. See The City of God XV.22–23.
There is therefore no doubt that, according to the Hebrew and Christian canonical Scriptures, there were many giants before the deluge, and that these were citizens of the earthly society of men, and that the sons of God, who were according to the flesh the sons of Seth, sunk into this community when they forsook righteousness.
Augustine, The City of God XV.23 (text).
What did he say in Questions on Genesis?
Augustine also addresses the question in Questions on Genesis, Question 3. He favors a human reading there while leaving a broader question about demons unsettled:
It is therefore more credible that righteous men, called angels, or sons of God, (Cf. Gen. 6:2) moved by lust, sinned with women, instead of angels, who could not commit that sin because they lack bodies; although certain demons have been evil with women, so many things are said and by so many people, that it is not easy to decide on an opinion on this question.
Augustine, Questions on Genesis 6, Question 3. Translation retained from this article’s 2023 version.
This is the same distinction that matters in The City of God: uncertainty about every report involving spirits does not make angels Augustine’s preferred explanation for the “sons of God” in Genesis 6.
What about “angels of God”?
Augustine knows that some copies of the Greek Scriptures use “angels of God” where others have “sons of God.” He does not ignore that wording. Instead, he argues that a human being can be called an angel in the sense of a messenger. He points to John the Baptist as an example of a person called a messenger, then appeals to the Genesis passage’s description of the offenders as men and flesh. In his reading, “sons of God” describes their standing by grace; it does not change their human nature. See XV.23, especially the discussion of manuscript readings and Genesis 6:3.
His position is firm about the identity of the figures in this passage, but narrower than a blanket claim about every spirit story. Augustine says he cannot settle whether certain spirits could have bodily relations with women. He also says he cannot believe that God’s holy angels were the fathers in Genesis 6. Those are different claims: he leaves one broader question unresolved while rejecting the angelic explanation of the biblical “sons of God.”
But that those angels were not angels in the sense of not being men, as some suppose, Scripture itself decides, which unambiguously declares that they were men.
Augustine, The City of God XV.23 (text).
Did Augustine deny the giants?
No. Augustine accepts that Genesis speaks of giants. What he denies is that their existence proves angelic parentage. He observes that unusually large people can arise from human parents, and he reads Genesis 6:4 as placing giants on the earth both before and after the marriages. He therefore treats the giants as part of human history in the narrative, not as a separate angel–human race. See XV.23.
Augustine also distances this reading from writings circulated under Enoch’s name. He grants that Jude refers to Enoch, yet questions whether the later books attributed to Enoch are genuine and rejects their authority as a basis for saying the giants had nonhuman fathers. This is Augustine’s judgment about those texts; it does not make the noncanonical Enoch tradition disappear from the history of interpretation.
How do the two passages in The City of God fit together?
The distinction matters. Book III, chapter 5 mentions fallen angels in passing and expressly sets the question aside. Book XV, chapters 22–23 returns to Genesis 6 in detail and identifies the “sons of God” as people descended from Seth who forsook righteousness. Reading the earlier question as Augustine’s final answer reverses the direction of his argument.
So Augustine’s answer to the reader’s question is clear, while his reasoning remains his own interpretation: Genesis 6 describes the corruption of godly humans, and the Nephilim or giants do not force a supernatural genealogy. Readers can compare that conclusion with other ancient readings, but Augustine should be represented by the position he actually adopts in his sustained treatment.
Sources: Augustine, Questions on Genesis 6, Question 3 (translation retained from the 2023 version of this article); The City of God III.5 in Volume I and XV.22–23 in Volume II, Marcus Dods translation (1871).
Jake Mooney is a lay researcher and the author of the novel The Descent of the Gods, with 25+ years studying Genesis 6. Chasing the Giants is where he brings Bible-first research together on the topic to help separate what we can really believe vs what is purely sensationalism.
