Genesis 4:3,4 - And in the process of time it came to pass, that Cain brought of the fruit of the ground an offering unto the Lord. And Abel, he also brought of the firstlings of his flock and of the fat thereof. And the Lord had respect unto Abel and to his offering.
CAIN'S OFFERING WAS REJECTED BECAUSE HE OFFERED THE FRUIT OF HIS OWN LABORS WHILE ABEL OFFERED A BLOOD SACRIFICE THAT PROPHESIED OF THE COMING OF CHRIST. THIS LED TO A RAGE IN CAIN THAT CAUSED HIM TO SLAY HIS BROTHER.
THE CROSS IS THE BASIS OF OUR ACCEPTANCE TO GOD AND REMAINS THE PRIMARY POINT OF CONFLICT BETWEEN CHRISTIANITY AND EVERY OTHER RELIGION, WHICH ARE ALL BASED ON MAN'S ACCEPTANCE THROUGH WORKS.
Ephesians 2:10 - For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them.
In the world "self-made" men and women are esteemed, but not so in Christ.
Our goal is to be fashioned and established by the grace of God, not our own efforts. In this way we are his workmanship, devoted to becoming what he wants us to be.
We are not working in order to gain approval, but because we love the one who loved us, saved us, and works through us.