Christian interpreters have traditionally offered several explanations. One identifies the sons of God as descendants of Seth, whose family line had preserved worship of the Lord. Their marriages with women from ungodly families may have contributed to the spread of corruption before the Flood.
Another interpretation, held by some early Christian writers and supported by certain modern commentators, understands the sons of God as fallen angels. This view draws attention to passages elsewhere in Scripture describing angels who sinned. However, the nature of such unions and their relationship to the Nephilim remain disputed.
A third explanation identifies the sons of God as powerful ancient rulers who claimed extraordinary authority and took women as they pleased. Under this interpretation, the passage describes the abuse of power and the growth of human violence.
The Nephilim themselves are commonly understood as unusually powerful or formidable men, although their precise identity remains uncertain.