Genesis 4:6-7 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 master it."
Our choices are important! Cain was angry because God did not regard him and his offering but only Abel and his offering. We do not know what exactly was wrong with Cain and his offering but it is likely that both his attitude and his offering were defective. In any case, it is clear that he did not do what was right (v. 7). God warns him that if he does not do well or what is right, then the sin crouching at the door will have the better of him. Therefore, he needs to rule over it (master it). The choice is his. The following verses (vv. 8f) show us that Cain did not heed God’s warning rather he chose to continue doing what was not right and gave the sin crouching at the door the opportunity to arise, which led to the murder of his brother Abel. If he had listened to God’s warning, God was with him to help him subdue the sin crouching at the door. Likewise, we have to be careful because sin is always crouching at our door and its desire is to devour us (cf. 1 Peter 5:8) but we have to master it. We cannot master it or rule over it on our own strength but the Holy Spirit is there to help us in this regard. Nonetheless, we have our part to play in deciding and making all the efforts possible to not give the sin a foothold in our lives.
May the Lord help us choose to do well, and rule over the sin that is always crouching at our door!