Thank you for contacting BibleAsk.
Cain’s offering was unacceptable to God first and foremost because it was not what God asked for. Cain reluctantly acknowledged the claims of God upon him. A spirit of rebellion made him comply to God’s command in a way of his own choosing rather than to follow precisely the plan ordained by God, which was to offer an animal sacrifice.
Cain offered a bloodless offering – fruits of the ground. Abel offered an animal sacrifice (Genesis 4: 2,3). Cain offered a gift that expressed no repentance for sin. The Bible teaches “without shedding of blood there is no remission,” for “it is the blood that makes atonement for the soul’” (Hebrews 9:22; Leviticus 17:11).
While Abel’s offering was a demonstration of faith in the blood of the future Savior (Hebrews 11:4), Cain’s offering, in contrast, was an attempt to earn salvation by his own efforts. Cain failed to realize that partial, formal compliance with the explicit requirements of God could not earn God’s favor.
When Cain noticed the absence of any visible sign of God’s acceptance of his offering, he burned with anger against God and felt fierce resentment towards his brother. There was no sorrow for sin in his heart. His behavior reflected that of an unrepentant sinner who does not yield to correction.
The rejection of Cain’s offering did not necessarily mean that God rejected Cain at this point. In mercy and patience, God was ready to give Cain another chance. “So the Lord said to Cain, “Why are you angry? And why has your countenance fallen? If you do well, will you not be accepted?” (Genesis 4:6, 7).
But instead of repenting of his sin, Cain’s heart hardened against God and he insisted on his evil ways. And his hate led him to kill his brother Abel. The Bible states that Cain’s “works were evil and his brother’s righteous” (1 John 3:12). How different things would have been for Cain if only he yielded to God’s love.
In His service,