What does Genesis 4:13 mean?

God has cursed Cain for the murder of his brother Abel. Cain's response shows that he is not repentant. Instead of acknowledging his sin and receiving the consequence, he complains that it is too much. He claims that he can't bear it. Not only has he lost his relationship with God and with his family, but God has removed Cain's livelihood. In the following verse, Cain will reveal that part of his objection is being driven from God's presence, losing that relationship and God's protection from harm. Even rebellious Cain understood he needed God's help to survive in the world.

And yet, there is no sense of repentance, remorse, or apology in Cain. As noted, this part of the Bible is extremely light on details. However, there is nothing suggesting that Cain is actually sorry for what He has done. All of his comments, and all of his actions later in this chapter, suggest selfishness and rebellion. Rather than asking God for forgiveness, Cain's only response worth recording is to moan that he is being punished beyond his ability to stand.