Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
The apostle resumes the thread of his instructions, by taking up as he does in all his epistles the moral consequences of his doctrine. He places the believer at the outset on the ground of God's mercy, which he had fully developed already. The principle of grace that saves had been established as the basis of salvation. The ground of all christian morality is now laid in this fundamental principle: to present our bodies as a sacrifice, living, holy, acceptable to God an intelligent service, not that of the hands, not consisting in ceremonies which the body could perform a simple but deep-reaching and all-efficacious principle. This was for man personally. As to his outward relationships, he was not to be conformed to the world. Neither was this to be an outside mechanical nonconformity, but the result of being renewed in mind, so as to seek for and discern the will of God, good and acceptable and perfect; the life being thus transformed.
This connects itself with the end of Chapter 6. It is not those sitting in heavenly places, imitators of God as dear children, but men on earth set free by the delivering power of redemption and grace, yielding themselves up to God to do His will. The exhortation follows the character we have seen to be that of the epistle.
Thus the christian walk was characterised by devotedness and obedience. It was a life subjected to the will of another, namely, to the will of God; and therefore stamped with humility and dependence. But there was absolute devotedness of heart in self-sacrifice. For there was a danger, flowing from the power that acted in it, of the flesh coming in and availing itself of it. With regard to this, every one was to have a spirit of wisdom and moderation, and to act within the limits of the gift which God had dispensed to him, occupying himself with it according to the will of God; even as each member has its own place in the body, and should accomplish the function which God has ascribed to it. The apostle passes on insensibly to all the forms which duty assumes in the Christian, according to the various positions in which he stands, and to the spirit in which he ought to walk in every relationship.
It is in Chapter 12 only that the idea of the assembly as a body is thus found in this epistle; and that, in connection with the duties of the members individually duties that flowed from their positions as such. Otherwise it is the position of man in his individual responsibility before God, and this met by grace, and then the delivered man, that is set before us in the Epistle to the Romans. The directions given by the apostle extend to the Christian's relationship with the authorities under which he is placed. He recognises them as accomplishing the service of God, and as armed with authority from Him, so that resisting them would be resisting that which God had established. Conscience therefore, and not merely force, constrained the Christian to obey. In fine he was to render to every man that which was due to him in virtue of his position; to leave nothing owing to any one, be it of whatever character it might excepting love a debt which never can be liquidated.