Worship at the Cherubim-guarded Gate

At the cherubim-guarded gate of Paradise the glory of the Lord was revealed, and hither came the first worshipers.... It was here that Cain and Abel had brought their sacrifices, and God had condescended to communicate with them.TA 63.4

Skepticism could not deny the existence of Eden while it stood just in sight, its entrance barred by watching angels. The order of creation, the object of the garden, the history of its two trees so closely connected with man's destiny, were undisputed facts. And the existence and supreme authority of God, the obligation to His law, were truths which men were slow to question while Adam was among them.—Patriarchs and Prophets, 83, 84.TA 64.1

[Cain and Abel] had been instructed in regard to the provision made for the salvation of the human race. They were required to carry out a system of humble obedience, showing their reverence for God, and their faith and dependence upon the promised Redeemer, by slaying the firstlings of the flock, and solemnly presenting it with the blood, as a burnt offering to God....TA 64.2

He [Cain] was unwilling to strictly follow the plan of obedience, and procure a lamb and offer it with the fruit of the ground. He merely took of the fruit of the ground and disregarded the requirement of God.... Abel advised his brother not to come before the Lord without the blood of a sacrifice. Cain being the eldest, would not listen to his brother....TA 64.3

Abel brought of the firstlings of his flock, and of the fat as God had commanded; and in full faith of the Messiah to come, and with humble reverence, he presented the offering. God had respect unto his offering. A light flashes from heaven and consumes the offering of Abel. Cain sees no manifestation that his is accepted. He is angry with the Lord, and with his brother. God condescends to send an angel to Cain to converse with him.TA 64.4

The angel inquires of him the reason of his anger, and informs him that if he does well, and follows the directions God has given, He will accept him, and respect his offering. But if he will not humbly submit to God's arrangements, and believe and obey Him, He cannot accept his offering. The angel tells Cain that it was no injustice on the part of God, or partiality shown to Abel; but that it was on account of his own sin, and disobedience of God's express command, why He could not respect his offering—and if he would do well he would be accepted of God.... But even after being thus faithfully instructed, Cain did not repent.... In his jealousy and hatred he contends with Abel, and reproaches him.... While Abel justifies the plan of God, Cain becomes enraged, and his anger increases and burns against Abel, until in his rage he slays him.—Spiritual Gifts 3:47-49.TA 65.1