“ Then the LORD said to Cain, "Why are you angry? Why is your face downcast? 7 If you do what is right, will you not be accepted? But if you do not do what is right, sin is crouching at your door; it desires to have you, but you must master it." Genesis 4:6
Cain and Abel, the sons of Adam and Eve, had made offerings to God. God had looked with favor on Abel’s offering, but not on Cain’s. The Bible doesn’t tell us specifically why. Probably it was the attitude of the heart. Also, it foreshadowed Jesus’ sacrifice for our sins with Abel’s sacrifice of the firstfruits of the flock compared to Cain’s sacrifice of the fruits of the soil.
Cain was angry and jealous of Abel. God told him that he didn’t need to be angry. All he had to do is what is right to be accepted: “…He is patient with you, not wanting anyone to perish, but everyone to come to repentance.” 2 Peter 3:9
God does not want anyone to go to hell; He has done all He can so people can live forever with Him in heaven: “…I take no pleasure in the death of the wicked, but rather that they turn from their ways and live…” Ezekiel 18:23, 33:11
God told Cain that sin was waiting to get him if he did not obey. The devil is always waiting for us to disobey. Our enemy in all situations, whether from within ourselves or from others is the devil: “For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms.” Ephesians 6:12
Then God told Cain he must master sin. How do we master sin? “Submit yourselves, then, to God. Resist the devil, and he will flee from you. Come near to God and he will come near to you. Wash your hands, you sinners, and purify your hearts, you double-minded. Grieve, mourn and wail. Change your laughter to mourning and your joy to gloom. Humble yourselves before the Lord, and he will lift you up.” James 4:7-10 We have to repent (change our mind about our sins which changes our actions) and do what God is telling us.
The sad news is that Cain never accepted God’s generous offer. He killed his brother and was forever separated from the presence of God. He was never repentant. He only complained that the punishment God was giving him was too much to bear. God generously made a concession, putting a mark on him so no one would kill him. Cain had it easier in this life, anyway.
The good news is that it is possible to do what God is telling us: “No temptation has seized you except what is common to man. And God is faithful; he will not let you be tempted beyond what you can bear. But when you are tempted, he will also provide a way out so that you can stand up under it.” 1 Corinthians 10:13 God Himself will provide a way to be free from sin.
Truths revealed in this verse are encouraging for those who are fighting against a sin that seems impossible to overcome. We learn from this verse that God wants us to be free. He loves each of us so much He sent His only Son to pay the penalty for our sins: "For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. For God did not send his Son into the world to condemn the world, but to save the world through him." Jon 3:16-17 All that is necessary is to believe in Him: "Whoever believes in him is not condemned, but whoever does not believe stands condemned already because he has not believed in the name of God’s one and only Son.” John 3:18 He has made a way to make it possible for us to be free from the consequences and the power of sin. We just have to work with Him and do what is right.
“Therefore, my dear friends, as you have always obeyed–not only in my presence, but now much more in my absence–continue to work out your salvation with fear and trembling, for it is God who works in you to will and to act according to his good purpose.” Philippians 2:12-13 If we obey (if we believe in Him which is shown by obedience) He is working in us to act according to His purpose—His good purpose. His purpose is for the good of His friends, which we are if we believe.