“well...well.” The Hebrew word is yatab (#03190 יָטַב), and it means to be good, to do well, to be pleasing, to make glad. There is a profound but unstated truth here in Genesis 4:7, and that truth is that God is the creator of the heavens and the earth, and humankind, and He makes the rules. It is God who defines and determines what is “right” or “good” and what is “bad” or “evil.” Arrogantly, humans and human society often act like they can set the rules of life; that they can determine what is good and what is bad. But humans are fallen creatures in a fallen world and are not righteous like God, but are basically selfish, egotistical, meanspirited, and ungodly. History has proved this over and over. Every generation sees the outworking of the evil in humankind in the fact that every generation faces war, crime, and people mistreating other people.
Furthermore, and importantly, although humans can often exercise somewhat effective control over other humans, they cannot control the earth or the spiritual battle that rages behind the scenes between godly forces, such as God and angels, and evil forces, such as the Devil and demons. It is demonic forces that cause natural disasters, famines, floods, plagues, and such evils. Only God’s blessing can mitigate against those disasters, and the Bible shows us over and over that His blessing comes when people are obedient to Him (cp. commentary on Lev. 18:25).
Also, in the final analysis, a person’s life here on earth is short but what is coming in the future is everlasting. Coming in the future is Judgment Day, when each person will stand before the God who created them and be judged either as righteous or unrighteous according to His standards, not the standards of any human society. The righteous will be granted everlasting life, while the unrighteous will be thrown into the Lake of Fire and suffer everlasting destruction. So here in Genesis 4:7 is a simple and profound statement of truth: if a person does “well” according to God’s rules, they will be accepted. If a person does not do well, they will fall prey to sin, and the wages of sin is death (Rom. 6:23), so they will be burned up in the Lake of Fire (Rev. 20:11-15). Given the choices before us, the decision should be easy: obey God; it is profitable in this life and the next.
[For information on how to get saved, see commentary on Rom. 10:9. For more on the destiny of the unsaved, which is annihilation in the Lake of Fire, see Appendix 5, “Annihilation in the Lake of Fire.” For more on the spiritual battle raging between Good and Evil, see commentary on Luke 4:6].
“will you not be accepted.” The Hebrew text is idiomatic and basically says: “will it not be lifted up?” The idiom refers to one’s face being lifted up to another if there is acceptance and agreement between you. Cain’s face fell when God rejected his offering (Gen. 4:5), but if he did God’s will his face would be lifted up. But the idiom is not easily understood in English, so many versions put the meaning of the idiom in their translation, as does the REV.
“sin crouches at the door.” The Hebrew word “sin,” usually a feminine noun, is constructed in the masculine here. Thus sin is portrayed as a real thing, an animal of the male gender, and may in this case even be a reference to the masculine noun, “serpent,” which occurs in Genesis 3. That sin is some kind of crouching creature, waiting to spring on its victim, is well portrayed by Everett Fox (The Schocken Bible: Volume 1, The Five Books of Moses). He translates verse 7, “If you intend good, bear-it-aloft, but if you do not intend good, at the entrance is sin, a crouching demon, toward you his lust—but you can rule over him.”
The NIV Study Bible text note on Genesis 4:7 says, “The Hebrew word for ‘crouching’ is the same as an ancient Babylonian word referring to an evil demon crouching at the door of a building to threaten the people inside.” Although the Devil and demons are always on the alert to be able to afflict people who turn away from God and godliness, there is an important truth in the Sin-Demon being at the door. Godly people can cleanse their houses of demonic materials and faithfully pray for the holiness and protection of their house, and that can keep demons from being able to enter, but demons may sometimes “wait at the door,” hanging around and waiting to find ways to afflict the inhabitants. God warned Cain about his sin and what could happen if he did not repent, but Cain ignored God’s warning and turned to the Devil for support and became “of that wicked one” (1 John 3:12). Cain committed the unforgivable sin, which is why he could not be forgiven, and he knew it (Gen. 4:13). When a concept like sin is portrayed as an animal, that is the figure of speech zoomorphism. [For more on zoomorphism and personification, see commentary on Prov. 1:20. For more on the unforgivable sin, see commentary on Matt. 12:31].