God's love of missions is shown here, just as it is everywhere. He wants people to worship Him, not to turn away. He is just, but that justice is mingled with grace and mercy. That is the only way any of us can be effective in winning others to Christ and having them truly born again. We must tell them both of Christ's mercy and forgiveness and of His holiness, unable to look upon sin. He is willing that none perish, but that all come to repentence. (2 Peter 3:9) But, He is also just, and Christ died for our sins (1 Cor. 15:3), becuase our sin is so bad to a Holy God that He required perfect blood for the remission of sin. Christ was punished in our place, and we can only be healed by His having suffered for us. (1 Pet. 2:24)
God wants people to love Him, and to see His goodness and mercy. That's why He spoke to Cain. We noted that His slaying of the lamb near the end of Genesis 3 was likely a Theophany. He could easily have just spoken in an audible voice, but that is uncertain. He could have been a Theophany only there and here, but not later, too.
What's important is that He gives Cain a chance. He awants Cain to explain, so He can help Cain avoid sin. Christ is always waiting for us to talk to Him, and seek His help. We fail miserably all too often, because we don't see any way out, we get scared, or something else. But, his mercies endure forever, and He is always wiling to hear us.
One other thing is worthy of note about this. God wants us to be happy and joyful. This is so clear elsewhere, such as in Philippians. The words "rejoice" and "joy" show up a lot there. God wants us to find joy in Him even in our struggles. That's where we often draw closest to Him. God wanted Cain to serve Him, but also wanted him to be joyful about it. He wanted CAin to accept this as a learning experience and avoid sinning any more.
One may ask why this is different than how He approached Adam and Eve. Remember that they had just brought sin into the world. it was perfect before then. the incredible change int he world meant God had to confront the problem right away.
Here, on the other hand, Cain and Abel had merely continued what had already been going on - sins such as lying, coveting, and son on, were growing. A plan of sacrifice for those sins had been put in place, to cover them until the Redeemer came to wash them away completely.
"But wait," one might say, "aren't all sins equally bad?" We must remember that the way God sees sin, and the way He deals with the consequences of individual ones, are two different things
All sin causes us to fall short of God's perfect glory. God can't touch any sin. if He had come the first time in all His glory, this sinful world would have perished. This is why, in Isaiah 6. the prophet feels he is "undone" - literally a dead man, cut off - after seeing God, in all His splendor, in His Heavenly temple. No person can see God, and live.
However, all sin does not carry the same consequences on Earth. The Mosaic law shows this - stealing is not met with the same punishment as murder, and so on. Common practice shows this - lying about one's age doesn't carry the same weight as cheating on one's taxes. Small sins can begin a slippery slope that lead to bigger sins, as Davis learned with Bathsheeba, when he lusted after her in 2 Samuel 11. However, God wants us to confess and forsake those small sins, so they don't become bigger ones later.
So it was that God lovingly approached Cain, so he could be won back to God, before his sin grew and made things worse. God sought to help Cain out of; an attitude of going against God's perfect plan.
