12. Let not sin then, etc. He now begins with exhortation, which naturally arises from the doctrine which he had delivered respecting our fellowship with Christ. Though sin dwells in us, it is inconsistent that it should be so vigorous as to exercise its reigning power; for the power of sanctification ought to be superior to it, so that our life may testify that we are really the members of Christ. I have already reminded you that the word body is not to be taken for flesh, and skin, and bones, but, so to speak, for the whole of what man is. ¹ This may undoubtedly be inferred from the passage; for the other clause, which he immediately subjoins respecting the members of the body, includes the soul also: and thus in a disparaging manner does Paul designate earthly man, for owing to the corruption of our nature we aspire to nothing worthy of our original. So also does God say in Genesis 6:3; where he complains that man was become flesh like the brute animals, and thus allows him nothing but what is earthly. To the same purpose is the declaration of Christ, "What is born of the flesh is flesh." (John 3:6.) But if any makes this objection -- that the case with the soul is different; to this the ready answer is -- that in our present degenerate state our souls are fixed to the earth, and so enslaved to our bodies, that they have fallen from their own superiority. In a word, the nature of man is said to be corporeal, because he is destitute of celestial grace, and is only a sort of empty shadow or image. We may add, that the body, by way of contempt, is said by Paul to be mortal, and this to teach us, that the whole nature of man tends to death and ruin. Still further, he gives the name of sin to the original depravity which dwells in our hearts, and which leads us to sin, and from which indeed all evil deeds and abominations stream forth. In the middle, between sin and us, he places lusts, as the former has the office of a king, while lusts are its edicts and commands.

13. Nor present your members, etc. When once sin has obtained dominion in our soul, all our faculties are continually applied to its service. He therefore describes here the reign of sin by what follows it, that he might more clearly show what must be done by us, if we would shake off its yoke. But he borrows a similitude from the military office, when he calls our members weapons or arms (arma); ² as though he said, "As the soldier has ever his arms ready, that he may use them whenever he is ordered by his general, and as he never uses them but at his command; so Christians ought to regard all their faculties to be the weapons of the spiritual warfare: if then they employ any of their members in the indulgence of depravity, they are in the service of sin. But they have made the oath of soldiers to God and to Christ, and by this they are held bound: it hence behoves them to be far away from any intercourse with the camps of sin." -- Those may also here see by what right they proudly lay claim to the Christian name, who have all their members, as though they were the prostitutes of Satan, prepared to commit every kind of abomination.

On the other hand, he now bids us to present ourselves wholly to God, so that restraining our minds and hearts from all wanderings into which the lusts of the flesh may draw us, we may regard the will of God alone, being ready to receive his commands, and prepared to execute his orders; and that our members also may be devoted and consecrated to his will, so that all the faculties both of our souls and of our bodies may aspire after nothing but his glory. The reason for this is also added -- that the Lord, having destroyed our former life, has not in vain created us for another, which ought to be accompanied with suitable actions.