Richard Beck, who blogs at Experimental Theology and is Professor and Department Chair of Psychology at Abilene Christian University, tackles the story of the Nephilim in Gen. 6.1-4. He revives the Sethite Hypothesis, under which “sons of God” are interpreted as the descendents of Seth (Gen. 5) and the “daughters of men” are interpreted as the descendents of Cain (Gen. 4).
The argument here is that the “image of God” is carried through the line of Seth. These “sons of God”–the descendants of Seth–“fall” when they begin to intermarry with the descendants of Cain (“the daughters of men”). And while it might seem that this argument is a bit stretched it is worth noting that some Gnostic sects saw Seth as the father of the children of God, the elect. In this we see a dualism where Seth and Cain function as the primordial ancestors of the “children of light/God” and the “children of darkness/Satan” respectively.
– Richard Beck, “The Nephilim”, Experimental Theology, 17 September 2012
The interpretation of “the sons of God”/”the sons of the gods” (בני האלהים) as the human descendents of Seth has been overtaken in modern scholarship by their interpretation as either divine beings or angels (with some interpreting them as kings or potentates). The most famous defence of the Sethite interpretation is Augustine’s explanation of the sons of God as Sethites, in City of God 15.23. Yet earlier identifications of בני האלהים as the descendents of Seth were made in a fragment of the early third century Chronographie by Julius Africanus preserved in Syncellus, and [there are related distinctions between Sethites and Cainites] in Philo’s early first century Quaest. in Gen. [1.79 but in relation to Gen. 4.25], and perhaps even [an even earlier Sethite interpretation of Gen 6.4] in the second century BC Sirach 16.7.
Have a read of Richard’s thoughts from his prison Bible study on Gen. 6.1-4, here.