For sin shall not have dominion over you: for ye are not under the law, but under grace.
For SIN shall not have dominion over you (as the slaves of a tyrant lord):
For ye are not under the law, but under grace - х hupo (G5259) nomon (G3551) ... hupo (G5259) charin (G5485). Hupo (G5259) with the accusitive denotes 'motion to underneath'-figuratively, 'moral subjection.'] The sense and force of this profound and precious assurance all depends on what is meant by being "under the law" and being "under grace." Mere philological criticism will do nothing to help us here. We must go to the heart of all Pauline teaching to discover this. To be "UNDER THE LAW," then, is first, to be 'under its claim to entire obedience on pain of death;' and so, secondly, to underlie the curse of the law as having violated its righteous demands (Galatians 3:10). And since any power to fulfill the law can reach the sinner only through Grace-of which the law knows nothing-it follows, lastly, that to be "under the law" is to be shut up under an inability to keep it, and consequently to be the helpless slave of sin. On the other hand, to be "UNDER GRACE," is to be under the glorious canopy and saving effects of that "Grace which bringeth salvation" and reigns 'through righteousness unto eternal life by Jesus Christ our Lord' (see the notes at Romans 5:20-21). The curse of the law has been completely lifted from off them; they are made "the righteousness of God in Him," and they are "alive unto God through Jesus Christ." So that, as when they were "under the law," Sin could not but have dominion over them, so now that they are "under grace," Sin cannot but be subdued under them. If before, Sin resistlessly triumphed, Grace will now be more than conqueror. (See the excellent remarks of Calvin here.)