And the LORD said unto Cain, Where is Abel thy brother? And he said, I know not: Am I my brother’s keeper? And he said, What hast thou done? the voice of thy brother’s blood crieth unto me from the ground.
The LORD had warned Cain just previous to this in verse 7 that if he did well he would be accepted and that if he didn’t do well sin lieth at the door. Yet immediately Cain rises up against his brother and slays him. So sin was waiting at the door, crouching at the door waiting for Cain to go through it and when his jealousy took him through the door sin pounced.
We are commanded to love the LORD with all our heart, soul and mind and to love our neighbor as our self. If Cain had chosen to practice this one principle he never would have gone through the door of sin.
When the LORD accepted Abel’s sacrifice but not his own, Cain became wroth and his countenance fell. Instead of concern about why his sacrifice was not pleasing to the LORD and instead of joy and happiness for his brother because his sacrifice was accepted, Cain became wroth. This path is in direct conflict with the command given for us to love the LORD and to love our neighbor as ourselves.
We all suffer from human emotions and misstep at times. We all misjudge situations and don’t respond as well as we could have at times. However when I choose to love the LORD with all my being and I choose to love my neighbor as myself I will be able to do well and avoid going through a door of sin. When I love the LORD and my neighbor as myself I will be concerned about why the LORD didn’t accept my sacrifice and I will be happy for brother that the LORD accepted his sacrifice. I will then be looking to see where I can do well.
Doing well means loving the LORD with all my being and loving my neighbor as myself. This is the thing that keeps me from going through the door of sin.