Genesis 4:5-7
"but on Cain and his offering he did not look with favor. So Cain was very angry, and his face was downcast. Then the Lord said to Cain, 'Why are you angry? Why is your face downcast? 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 rule over it. '"
This is an amazing twist. Cain protects himself, lusting after and saving the best for himself, causing him to withhold from God. God’s response however, is to having grace towards him.
Cain had a choice. He had the opportunity to go back to God, open up his heart, give his best, and worship God fully. However, in the next verse, Cain doesn’t do this and instead invites his brother Abel to a field and kills him.
This story highlights the choice Cain had. Just as he had a choice to withhold from God, we have a choice whether or not to withhold from our spouse. He had the power to not sin, to not close his heart or create strategies to harm, which lead to Abel’s murder. He could have decided not to manipulate, blame others, or be angry and cause harm.
Cain could have overcome the sin of withholding by doing what was right. We as believers in Christ have the power through the Holy Spirit in us to choose not to sin or be mastered by it. Sin is a parasite that if you take in through the wrong choice, can feed off of you and grow.