The Bible is not a set of disconnected individual stories, each of which has a lesson about how to live life. The Bible is primarily a single storyline. A single story that shows us what’s wrong with the human race and what God is doing about it.

In Genesis 3 and 4 we learn about sin through the sad narrative of Cain and Abel. God, when speaking to Cain, uses a remarkable image when He told Cain that if you don’t do what is right, sin is crouching at the door—that it desires to have you. The image is of a predatory animal crouching, lurking, ready to spring and kill.

God was personally explaining to Cain how the entrance of sin can become a growing presence in your life. When you sin, it’s not over. It’s not simply a single action. It’s a force. It’s a power. It can actually become a presence in your life. It can stay with you and affect you. Think about a habit and how the things of the habit become easier to repeat; and then still easier … and progressively harder to stop doing.

Sin doesn’t just fade away. It creates a presence, and repeated sin creates a mindset—an attitude that affects others. Haters tend to be hated. Cowards tend to be deserted. He who lives by the sword will die by the sword. Sin hardens you. It becomes a presence in your life that will also affect those around you. It’ll poison your relationships with other people in ways that you don’t see.

The crouching sin image also gets across the idea that sin hides, crouching out of sight. If you see a crouching lion, you can avoid it. If you don’t, you’re dead. The things that are most going to ruin you, or are ruining you, or are making the people around you miserable, are the “hidden” things you least see or admit, the attitudes and actions that you’re in denial about, that you rationalize away or minimize, that you justify, whenever somebody brings them up. Those are crouching lions in your life—ones that can eventually take you out. As long as you think your obsession is okay, you’re vulnerable, blind. You’re in denial.

And then there’s the subtlety of sin. Abel is accepted by God, but Cain is rejected. The narrative seemingly divides them into good and bad. That’s the traditional interpretation, good people are those who uphold moral values and bad people are those who don’t and who live any way they want. Some classify good and bad as religious and heathen, liberal and conservative, or capitalist and socialist. They create neat little lines between their concept of right and wrong.

But you don’t see that with Cain and Able. One of them isn’t running around boozing it up and womanizing, and the other prayerful and pious, and bringing their offerings. You don’t see one working hard and the other living off welfare. The only difference is that one is a farmer, growing produce, and the other a rancher, raising animals.

“In the course of time Cain brought to the Lord an offering of the fruit of the ground, and Abel brought of the firstborn of his flock and of their fat portions.” They were both bringing an offering to God, but then God blesses and prospers Able, but not Cain. Why?

It’s a matter of the heart. The clue is when Cain offered “some” of the fruits of the soil, but Abel brought “fat” portions from the first born of his flock. In Abel’s case the income of a rancher is the number of livestock born that year. If the rancher wants to be cagey, he can wait and give the Lord his offering after seeing how many animals are born. If 12 animals were born that year and he gives one or two, he tithed. But what if he gave 1 of the first born, but at the end of the day only two or three were born that year? The one you gave now becomes 50%.

Did that mean Cain didn’t have faith in God, or that he didn’t believe that God existed? No, Cain was talking directly with God about the situation, so that wasn’t the problem. He knew God, he knew that God exists.

There’re two reasons to give God an offering. One is in gratitude for salvation, the other as a means of salvation; one God blesses, the other wants God’s rewards. If you see yourself as a sinner saved by grace, that He saved you in spite of yourself, He’ll honor that and care for you. If you depend on your works to prove yourself to God, you are trying to put God in your debt, “I worked, You reward me.” Cain and Abel are both hard working, they both believe in God, they both try to do well; the difference is the trust factor. Both had faith, only one had trust.

Back to the story … grace and justice. After the fall, when God comes to Adam and Eve, He asks them what they’ve done. At least Adam and Eve are kind of abashed and sheepish about it. They’re talking with God, Adam saying my wife made me do it and the wife saying the serpent made me do it, but when the Lord asked Cain where is your brother? What have you done? Cain retorts, am I supposed to keep tabs on that guy?

There are two things about God here—His grace and His justice. First, He’s asking questions. He didn’t show up after Adam and Eve’s sin and say, how dare you do what I told you not to do? He asks, what have you done? Where have you been? What’s going on? Similarly, he doesn’t show up and say to Cain, how dare you question who I bless and who I don’t bless. Who do you think you are?

He shows up and asks to talk. He was trying to get them to understand themselves and their hearts. He was trying to bring them along. He said to Cain, I see you’re downcast, depressed. He was trying to get Cain to understand his heart, where he was heading. Look at the tenderness of it.

God told Cain the truth, that it wasn’t Abel’s fault that he was depressed, and it wasn’t God that caused the anger he’s feeling. It was because of his own actions and attitudes and to watch out. God didn’t want crouching sin to master Cain. He didn’t want to see Cain perish.

That’s the grace of God, the love of God. But then God goes on to say, your brother’s blood cries out to me from the ground. God can’t just shrug off the violence and terrible things that happen. He can’t just let sin go. He’s a righteous God. He wants to save us, but He’s also just, and justice must be served.

1 John 1:9 doesn’t say if you confess your sins, He is faithful and merciful to forgive us our sins and to cleanse us of all unrighteousness. It says, He’s “faithful and just.”

Trust Him in all things so your identity is no longer based on your performance. You can have faith without trust, but you can’t have trust without faith. The world needs a lot more Ables. The Cains are out there killing each other, exploiting each other, lying about each other, elbowing each other around. Sin is mastering them. The blood of Jesus Christ cleanses us from all unrighteousness. Go and learn what that means.

— Tim Keller