What does Genesis 6:1 mean?
The previous chapter covered the lineage of Noah, through each generation from Adam through Seth, and their sons. At the start of chapter 6, Genesis stops to take a look at the larger world from God's perspective. In brief: He doesn't like what He sees. Mankind's actions and thoughts are completely evil (Genesis 6:5). Seeing how far man has fallen since being evicted from Eden causes God substantial grief (Genesis 6:6).Verses 1 and 2 are part of a single thought. Though not many women have been mentioned in the text thus far, daughters are being born as humanity expands across the face of the earth. As we'll see, those human women are attracting the attention of a group called "the sons of God." No further description is given of these men, which means their exact identity is not particularly important. If it was, Scripture would have provided additional details.
Most likely, this reference to the "sons of God" is a challenge to ancient perceptions of royalty. God is about to judge the world with a flood. Not even the children of humanity's kings and emperors, who often claimed to be divine, will be spared.