What does Genesis 4:24 mean?

The previous verse describes Lamech's bold and seemingly arrogant announcement to his wives that he had killed a young man for striking and/or wounding him. We don't know the whole story, but it sounds as if Lamech's response was out of proportion to what was done to him. Lamech uses the same Hebrew word to describe his action as Genesis 4:8 and Exodus 2:14, both referring to murderous acts.

Lamech apparently knew Cain's story well, including the part about how God had marked Cain with a sign. This was meant to back up God's promise to deliver vengeance seven-fold on anyone who killed Cain for killing Abel. Lamech claims the same protection for himself, but without God's apparent endorsement. Or perhaps he is declaring that he and his people will deliver the vengeance themselves without God's help. It's hard to know.

If Lamech is claiming God's protection, it shows that he still carries an awareness of God as protector. But that would also imply a deeply corrupt understanding of God, believing that God's power and protection could be presumed upon. Another possibility is that Lamech is being defiant and arrogant—"spitting in the face of God," so to speak—and celebrating his own evil.

Statements like this are key to understanding the context of the flood, where mankind is described as being deeply, perversely depraved (Genesis 6:5).