Adam is speaking therefore in this passage not only of the sin of Cain, but of sin in general; showing what the real nature of sin is. For that which was the state of Cain is the state of all men. Before he offered his sacrifice Cain proudly boasted of the privileges of his primogeniture; he despised his brother and assumed to himself the first place in all things. Sin was then lying still and asleep; but it was "lying at the door;" that is, in a place or state in which it was likely to be disturbed. For it is by "the door" that we go in and out, and therefore a place by no means adapted for a long sleep. And this is also the very nature of sin. Although it does lie asleep, yet it lies in a place where it is not likely to sleep long, for Christ says, "There is nothing covered that shall not be revealed," Math. 10:26. The wicked man thinks indeed that his sin is asleep and hidden; but it lieth asleep at "the door," and at length it is awakened by conviction, brought to light, and made known: for "at the door," and rest and sleep are things directly opposed to each other. For as darkness is opposite to light, so is sleep to an unquiet place; they are things contradictory to each other in their very nature. In this manner therefore may the present passage be interpreted in its reference to Cain's past sin.
And if you explain these same words in their reference to the future sin of Cain, their meaning is this, "If thou shalt harm thy brother, and indulge the wrath conceived in thy mind, I tell thee that thy sin will indeed lie asleep; but it will lie asleep at the door; that is, in a place where it will surely be disturbed; and therefore, it is impossible but that it must be awoke and roused up, when as a furious beast it will lay hold upon thee." And so the event proved. For after Cain had committed the murder, while he was burying his brother alone, his sin was asleep. But how long? No longer than until the sound of that voice of God reached his ears, "Where is Abel, thy brother?" The present words of Adam therefore are a true description of all sin. It always "lieth at the door." For such is the nature of the minds of men, that as long as they escape the eyes of men, they think their sin will lie hidden and unknown. But unless they do well; that is, unless they believe that God will pardon their sin through Christ, it will surely be awakened and revealed to their torment and destruction.
The figurative proverb therefore which lies in these words of Adam contains the most solemn truth, that nothing remains hidden, but that all things are revealed and made known, as the Apostle Paul also says, "Some men's sins are evident, going before unto judgment," 1 Tim. 5:24. Hence we see the judgment of God in an especial manner in the cases of criminals. How many persons are murdered in secret and yet the authors of those unnatural and horrible crimes are brought to light by means the most wonderful. The grave admonition therefore of Adam to his son Cain is that he would guard against indulging in sin, resting fully assured that it would not remain hidden, but that God would certainly bring it to light and punish it. The poets of old did not wander far from this great truth when they represented Cupid, the god of lustful desire, naked but blind also. For as our sin seems to us to be hidden, we think that it is hidden from all others also. But God at length brings to light and reveals things the most deeply concealed.
I believe therefore the meaning of these words of Adam, which I have thus given, is their true and simple sense. By them the father is admonishing the son to believe in God and in the promised Seed; assuring him that if he does so, God will show himself merciful unto him. But, says the father, if thou follow the lusts of thy heart, thy sin will indeed lie at rest in thy soul; that is, it will appear to thee to be concealed and hidden, but it will be lying all the time "at the door;" that is, in a place where it cannot lie long asleep or out of sight. For that which "lieth at the door" is beheld by all who enter in and by all who go out.
Let us not forget however, as I before observed, the grand and principal truth taught by this portion of the Holy Scriptures, that God from the very beginning of the world is One who judgeth between the flesh and the spirit, and who respecteth not the dignity of the person or his works. For God hath here respect unto Abel, not moved by any work which he performed, but simply by his faith in which he offered his sacrifice. But unto Cain God had not respect; not because the offering of Cain was less splendid or sumptuous than that of Abel, but because he had not faith, and therefore his primogeniture profited him nothing.
And this is a very powerful argument against the Jews, who, as John tells us, gloried in their race and descent, boasting that they were the children of Abraham, John 8:33. If therefore the honor and prerogative were anything in God's sight, Cain certainly had wherein to glory. And what avails also the glorying of the Jews that God spoke unto them by Moses? Are we to conclude, think you, that Adam, the first teacher, was a teacher less than Moses? No! Adam was greater than Moses and superior to him in many respects. He did not teach like Moses circumcision, nor the other legal ceremonies, which were necessary to a stiff-necked people to prevent them from superstition, but Adam taught faith in the promised Seed, which should bruise the serpent's head. All the primogeniture of Cain therefore and all his other privileges and his works profited him nothing; for God had respect only to faith in the promised Seed. Hence it is that Paul plainly says to the Jews in the New Testament, "Know therefore that they that are of faith, the same are the children of Abraham," Gal. 3:7. And Evangelist John says the same things concerning the Jewish people, "But as many as received him, to them gave he power to become the children of God, even to them that believe on his name: who were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God," John 1:12, 13.
I believe therefore that the above interpretation of the words of Adam is their original and true meaning. For, first of all, it is in perfect accord with the fundamental truth of the holy Scripture and with the sacred matter itself spoken of. And secondly, it does not violate any law of grammar, and it moreover tends to illustrate beautifully and variously by its figures the divine things contained in the words used by Adam. But the Rabbins, being ignorant of the things spoken of by Adam, are not at all helped out of the difficulty by all their knowledge of the terms employed in the patriarch's speech. How absurd for instance is the opinion of some, who apply the expression, There shall be a "lifting up" to the "fallen countenance" of Cain. As if Adam had said, "Then thou shalt be able again to lift up thy countenance, which is now wholly changed and fallen." These absurdities are indeed properly noticed by all our more recent commentators, to whom also our thanks are due, for their faithful labor in translating the original text grammatically. But true theology is indispensable, which alone can rightly judge of and rightly teach the things spoken of in the Holy Scripture.
V. 7b. And unto thee shall be its desire, but do thou rule over it.
Some men have most absurdly wrested this passage to prove by it free will. But it is perfectly evident that Adam does not here really affirm that Cain could do what he advised him to do. He is only admonishing or entreating him to do it. For it by no means follows that we can do what we are commanded to do. "The desire of sin," Adam here says to Cain, "shall be toward thee;" that is, as Paul expresses it, "Sin is in thy members," Rom. 7:5. Again, "The flesh lusteth against the spirit," Gal. 5:17. "But thou shalt not be eternally condemned, because thou feelest this motion of sin in thy members. If sin entice thee, do thou rule over it by faith. Suffer it not to rule over thee, or thou shalt perish for ever." Likewise Paul commands in Rom. 8:13, "By the Spirit put to death the deeds of the body."
This part of Adam's speech therefore is intended to bring us to acknowledge what the life of the godly in the flesh is: namely, that it is a perpetual struggle of the spirit against sin. Those therefore who sleep and snore, and prepare themselves not for this fight, are easily vanquished. Adam however appears to wish, by this his speech not only to admonish his son to guard against sin in the future, but also to comfort and lift him up from his distress on account of the past; for he beholds his son both filled with anguish on account of the divine rejection and now also tempted to revenge. But says Adam to his son, "Rule over thy sin, and thou shalt find God merciful. Believe in him, and he will pardon thy sin."