The story of Cain and Abel is a familiar one. Abel brings an approved sacrifice to God and is blessed. Cain brings an unacceptable sacrifice and is corrected by God. Seeing Cain's anger, God continues the conversation. "Sin is crouching at your door," He tells the older brother. "It desires to have you. But you can have mastery over it." Cain refuses to take mastery over his emotions, and instead takes mastery over Abel, committing the first murder.
It is interesting to notice that God assumes that Cain is able to make the right choice. He gives Cain more moral power than we often think we have. Cain is not portrayed as "enslaved" to his emotions, but rather as one who can take control of his passions. So why doesn't Cain "do the right thing?" I'm not sure we can know, but I'd like to hazard a guess that it's connected to desire.
What does Cain desire? Cain desires that God accepts his sacrifice. Cain wants God's approval. The problem is that Cain sees a conflict in the different ways that desire is met. He wants to receive God's approval on his own terms. It's not clear if he should have brought fat portions of a lamb himself, or whether he didn't bring the "first fruits" of his harvest. Both will be acceptable sacrifices in the future Jewish system. But he is unwilling to have his desire met in the way that God prescribes.
It's interesting to think of the role of desires in our lives. Listening to some tapes on Buddhism lately, I'm intrigued by the importance placed on the denial of desire as a way of reaching nirvana, a state of peace. Some Christians, I believe, think we should follow this path. They see desire as the root of all sin, distrusting what their hearts yearn for. In this worldview, renunciation of desire is the path to righteousness.
The problem is, this way of thinking can set up a false dichotomy. Either we follow our desires and sin, OR we deny our desires and become holy. But I think there is a third way- one of acknowledging our desires, and then allowing them to go through a purifying process in the light of God's desires. Did Cain think God was making a judgment on his chosen occupation of farming (if indeed God was asking for an animal sacrifice)? Was he embarrassed by being found out (if he offered less than the best of his produce)? Something pushed a button in Cain, resulting in his anger. And instead of letting that anger show him what was true in his heart, he coddled it, and allowed it to fuel feelings of resentment toward God, which then were turned toward Abel.
What if Cain would have been open to his anger? Perhaps there was the begining of jealousy between him and his younger brother - the first siblings and perhaps the first sibling rivalry. God could have spoken into that situation, validating both livelihoods, showing the importance of community. Or Cain might have been tempted to hold back the best for himself, and God could have shown the blessings of generosity.
We all have true desires, desires to be valued, to be signficant, to provide appropriately for ourselves, to be part of loving community. Renouncing these desires is renouncing what it means to be human. But holding them up to the scrutiny of God turns them from human desires into holy desires. When what we desire mirrors what God desires, we are free to let our hearts lead us toward what is truly good.