Genesis 4; Matthew 4; Ezra 4; Acts 4
it took only one generation for the human race to produce its first murderer (Gen. 4). Two reflections:
(1) In the Bible, there are many motives behind murder. Jehu killed for political advantage (2 Kings 9–10); David killed to cover up his adultery (2 Sam. 11); Joab murdered out of revenge, and out of the fear of having his privileged position usurped (2 Sam. 3); some of the men of Gibeah in Benjamin killed out of unbridled lust (Judg. 19). It would be easy to enlarge the list. On the occasion of the first murder, the motive was sibling rivalry out of control. Cain could not bear to think that his brother Abel’s offering was acceptable to God, while his own was not. Instead of seeking God so as to improve his own sacrifice, he killed the man he saw as his rival.
What is common to all these motives is the assumption entertained by the murderer that he or she is at the center of the universe. Even God must approve what I do; if not, since I cannot kill God, I will kill those whom God approves. Instead of the glorious situation that obtained before the Fall, when in the minds of God’s image-bearers, God himself was at the center, and loved and cherished as our good and wise Maker and Ruler, now each individual wants to be the center of the universe, as if saying, “Even God must serve me. If he does not, perhaps it is time to invent new gods.…”
Among the shocking elements in the murder of Cain is the stark fact that Cain’s nose is out of joint because he does not have God’s approval. The fatal sibling rivalry lies in this instance in the domain of religion. No matter: once I insist on being number one, I must be number one in every domain. Sad to tell, if the constraints of culture and fear of the penal system restrain me from outright murder, they are unlikely to restrain me from the kind of hate that the Lord Jesus insists is of the same moral order as murder (Matt. 5:21–26). So while the motives for murder are superficially many, at heart they become one: I wish to be god. And that is the supreme idolatry.
(2) In the Bible, the innocent are sometimes murdered. In this account, Abel is the righteous brother, yet he is the one who is murdered. From this fact we must reflect on two things. First, the Bible is utterly realistic about the horrible cruelty and unfairness of sin. Second, already by way of anticipation, we quietly recognize that if ultimate redress and justice are possible, God must intervene—and the books can only finally be squared after death.
 Carson, D. A. (1998). For the love of God: a daily companion for discovering the riches of God’s Word. (Vol. 1, p. 25). Wheaton, IL: Crossway Books.