Genesis 4:6 And the Lord said unto Cain, Why art thou wroth? and why is thy countenance fallen? 7 If thou doest well, shalt thou not be accepted? and if thou doest not well, sin lieth at the door.
[Patriarchs & Prophets pp 72] Cain came before God with murmuring and infidelity in his heart in regard to the promised sacrifice and the necessity of the sacrificial offerings. His gift expressed no penitence for sin. He felt, as many now feel, that it would be an acknowledgment of weakness to follow the exact plan marked out by God, of trusting his salvation wholly to the atonement of the promised Savior. He chose the course of self-dependence. He would come in his own merits. He would not bring the lamb, and mingle its blood with his offering, but would present his fruits, the products of his labor. He presented his offering as a favor done to God, through which he expected to secure the divine approval.
Cain obeyed in building an altar, obeyed in bringing a sacrifice; but he rendered only a partial obedience. The essential part, the recognition of the need of a Redeemer, was left out. So far as birth and religious instruction were concerned, these brothers were equal. Both were sinners, and both acknowledged the claims of God to reverence and worship. To outward appearance their religion was the same up to a certain point, but beyond this the difference between the two was great. “By faith Abel offered unto God a more excellent sacrifice than Cain.” Hebrews 11:4. Abel grasped the great principles of redemption.
He saw himself a sinner, and he saw sin and its penalty, death, standing between his soul and communion with God. He brought the slain victim, the sacrificed life, thus acknowledging the claims of the law that had been transgressed. Through the shed blood he looked to the future sacrifice, Christ dying on the cross of Calvary; and trusting in the atonement that was there to be made, he had the witness that he was righteous, and his offering accepted. Cain had the same opportunity of learning and accepting these truths as had Abel. He was not the victim of an arbitrary purpose. One brother was not elected to be accepted of God, and the other to be rejected. Abel chose faith and obedience; Cain, unbelief and rebellion. Here the whole matter rested.
Hebrews 3:12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. 13 But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.
May God add His blessing to the study of His word. "Good night" and God bless!