14 The first clause in verse 14, “For sin will not have dominion over you” is a statement of assured fact and should not be interpreted as imperative nor as pointing to a blessing reserved for the future. As in instances noted already, the future tense here also expresses the certainty of that which is affirmed. As indicative rather than imperative the assurance affirmed makes valid and relevant the exhortations in verses 12 and 13 and provides the encouragement and incentive to the fulfilment of these imperatives. Obedience to the latter is supported by the assurance that God’s grace insures the realization of what is contemplated in the exhortations.
The second clause in verse 14, “For ye are not under law but under grace” gives the reason why sin will not exercise the dominion. “Law” in this case must be understood in the general sense of law as law. That it is not to be understood in the sense of the Mosaic law as an economy appears plainly from the fact that many who were under the Mosaic economy were the recipients of grace and in that regard were under grace, and also from the fact that relief from the Mosaic law as an economy does not of itself place persons in the category of being under grace. Law must be understood, therefore, in much more general terms of law as commandment. In order to understand the force of the clause in question it is necessary to state what law can do and what it cannot do, and it is in the light of what it cannot do that the meaning of “under grace” will become apparent. (1) Law commands and demands. (2) Law pronounces approval and blessing upon conformity to its demands (cf. 7:10; Gal. 3:12). (3) Law pronounces condemnation upon every infraction of its demand (cf. Gal. 3:10). (4) Law exposes and convicts of sin (cf. 7:7, 14; Heb. 4:12). (5) Law excites and incites sin to more aggravated transgression (cf. 7:8, 9, 11, 13). What law cannot do is implicit in these limits of its potency. (1) Law can do nothing to justify the person who has violated it. (2) Law can do nothing to relieve the bondage of sin; it accentuates and confirms that bondage.
It is this last feature of the impotency of the law that is particularly in view in the clause in question. The person who is “under law”, upon whom only law has been brought to bear, whose life is being determined by the resources of law, is the bondservant of sin. Hence to be “under law” is to be the bondservant of sin. It is in this light that “under grace” becomes significant; the word “grace” sums up everything that by way of contrast with law is embraced in the provisions of redemption. Believers have come under all the resources of redeeming and renewing grace which find their epitome in the death and resurrection of Christ. The virtue which ever continues to emanate from the death and resurrection of Christ is operative in them through union with him. All of this the expression “under grace” implies. And, in terms of this passage and of the subject with which it is concerned, there is an absolute antithesis between the potency and provisions of law and the potency and provisions of grace. Grace is the sovereign will and power of God coming to expression for the deliverance of men from the servitude of sin. Because this is so, to be “under grace” is the guarantee that sin will not exercise the dominion—“sin will not lord it over you, for ye are not under law but under grace”.
John Murray, The Epistle to the Romans, vol. 1, The New International Commentary on the Old and New Testament (Grand Rapids, MI: Wm. B. Eerdmans Publishing Co., 1968), 228–229.