After murdering his brother, Cain cried out, "My punishment is more than I can bear: Today, you are driving me from the land, and I will be hidden from Your Presence. I will be a restless wanderer on the earth, and everyone who finds me will want to kill me."
Cain's curse, which he himself recognized, was a complete reverse of the original harmony, or balance, created by God--a deep connection between God and mankind, between man and the earth, and between man and woman/other men.
When Adam walked with God in friendship, the earth produced abundance in accord with the blessing of God, and when Adam saw Eve, he exclaimed, "This at last is bone of my bone and flesh of my flesh..." There was a deep-down everlasting freshness between man and the earth, and between man and woman.
With Adam's alienation from God came also alienation from the abundance of the earth (now, thorns and thistles will grow along with the fruit of the land) and alienation from Eve---
the woman you gave me enticed me to sin. (Now it's God's fault.)
By the time of the second generation, the alienation has been passed on and increased: man against God, the land against man, and man against his brother. That is the problem with sin; what is "tolerable" in one generation increases to the point of intolerable in succeeding generations. How does one stop the process?
In Christ Jesus, the curse is nailed forever to the cross and destroyed: alienation against God is patently forever forgiven; alienation of man against his brother is destroyed---
Father, forgive them, for they know not what they do; and the thorns on the head of the Savior are taken with Him to the grave. The curse of Cain is reversed forever.
The prophecy of Isaiah 55 says this:
Yes, in joy you shall depart,
in peace you shall be brought back;
Mountains and hills shall break out in song before you,
and all the trees of the countryside shall clap their hands.
In place of the thornbush, the cypress shall grow,
instead of nettles, the myrtle.
This shall be to the Lord's renown,
an everlasting imperishable sign.
When the "second Adam" was taken from the ground, a "new race" of people began again. Mankind's inherited alienation from God is replaced with the continual indwelling Presence of His Spirit. Alienation from the land is replaced with overflowing abundance, and, according to Paul, the Christ has destroyed in His own body "the dividing wall of hostility.... No longer Jew and Gentile; no longer male and female, no longer servant and master---but all are one in Christ Jesus."
He has reversed the inherited curse of alienation. This is indeed "Good News!"