Thank God for the shedding of the blood of Jesus! By it we have the remission of our sins. My wife can testify that almost every time we pray together the first word I say is, "Lord, we come to You by Your blood. Lord, cleanse us with Your blood. How we need the covering of Your blood!" While we are in the old creation, we still have a dirty, defiled element within us. Therefore, we need the cleansing of the blood of Jesus. Many times I have said to the Lord in my prayers, "Lord, we must pass through the altar. We need You to be our offerings. Lord, we take You as our sin offering and we offer You the fat." Cain missed the mark. He rejected the way of shedding of blood and took the way of Satan.
When the Apostle Paul was in the Jewish religion, he surpassed many of his equals (Gal. 1:14). However, he did not at that time obtain God's righteousness. In Philippians 3:9 he spoke a deep and excellent word: "And be found in Him, not having my own righteousness which is of the law, but that which is through the faith of Christ, the righteousness which is of God based on faith." Paul did not want to be found in himself, having his own righteousness; he wanted to be found in Christ, having the righteousness which is of God. We, like Paul, need to be found in Christ. That He is our righteousness is expressed by the words of a well-known hymn: "God's Christ, who is my righteousness, My beauty is, my glorious dress." Christ, as God's righteousness, is our covering under whom we stand. God has put us into Christ and made Him our righteousness (1 Cor. 1:30). We stand under His covering. We are one with Him. He, Himself, His very person, not one of His attributes, is our righteousness.
In Romans 10:3 Paul spoke of the unbelieving Jews, saying, "For they, being ignorant of God's righteousness, and seeking to establish their own righteousness, did not submit to the righteousness of God." Those Jews were the true followers of Cain. Cain was their forerunner, setting an example of attempting to establish his own righteousness and of not submitting himself to God's way of taking Christ as his righteousness. I say again that this is the way of Cain. Whenever we, outside of Christ, try to do good to please God, in the eyes of God we are following the footsteps of Cain. Never do that. According to God's revelation, we must recognize that worshipping God in our own way is an insult to Him.
Although God was merciful to Cain, he did not repent. God had the legal ground to sentence Cain to death, but He did not do it. Instead, He warned him that sin was crouching at the door, waiting for the opportunity to seize and devour him (Gen. 4:7). In that word of warning God indicated that sin was a person, Satan, that his desire was for Cain, and that Cain had to overcome him. Cain neglected God's warning, only caring for his own way. He did not repent, return, or change. He insisted on his own way unto the end, even unto death. So, he was absolutely gained by Satan and became one with the Devil (John 8:44). Hence, 1 John 3:12 says that he was out "of the evil one."