Was Cain let off too lightly for murder, according to the biblical account?

Click to join the conversation with over 500,000 Pentecostal believers and scholars

The text in question is Genesis 4:11-13 where God decrees Cain’s punishment for murdering his brother:

"And now art thou cursed from the
earth, which hath opened her mouth to receive thy brother’s blood from
thy hand. When thou tillest the ground, it shall not henceforth yield
unto thee her strength; a fugitive and a vagabond shalt thou be in the
earth. And Cain said unto the Lord, My punishment is greater than I
can bear." (A.V.)

What biblical reasons might there be for God not striking Cain dead?

And when God decrees a curse, what does that curse fully entail?

Finally, why did Cain claim that the punishment given would be greater than he could bear?

The chapter itself should provide sufficient evidence to avoid mere opinion-based answers, so if answers could refer to the context of those three verses, and any other hermeneutical standards, that would be appreciated.

EDIT: In view of some points raised, may I point out that I never mentioned any "law for murder" – deliberately – because there was no law about murder at that time, that the Genesis account mentions. Cain committed the first murder according to the text. Later on came legal requirements (as recorded in the Bible) for putting a murderer to death if there were two or more reliable witnesses, who were to be the first to cast the stones that would result in death. But I am not asking for a comparison with that; I’m seeking to find out what the punishment actually was, and why Cain felt it was unbearable for him. He didn’t think he was being let off too lightly, according to the text.