What does Genesis 6:2 mean?

This fascinating and much-debated verse concludes a thought begun in the previous one. As humanity began to expand across the earth, human daughters were born. These human women were attractive to the "sons of God." The sons of God took as wives any of the women they chose. So who were the "sons of God"? Several ideas have been offered by scholars over the centuries.

Some have suggested that the sons of God are the men of the line of Seth described in the previous chapter, while the "daughters of men" are from the line of Cain. This idea doesn't seem to fit, however, with what we're told in the following verses.

Many scholars believe these "sons of God" to be angels or demons (fallen angels)—or to be human men possessed by demons. This could also explain God's apparent objection to these "sons of God" and their offspring.

Finally, others suggest "sons of God" was a designation given to the human rulers of the time. Human kings and lords throughout history have often claimed to be divine to bolster their own authority. Perhaps these were merely powerful men, taking their pick of the women of the earth. This would fit with the ancient practice of taking many wives or having a harem of sexual servants. In the context of the upcoming flood, that would make this passage a refutation of their claims to divinity. Even the so-called divine rulers will be judged by the One True God in the flood.