Romans 7:13

Was then that which is good, made death unto me?
&c.] An objection is started upon the last epithet in commendation of the law; and it is as if the objector should say, if the law is good, as you say, how comes it to pass that it is made death, or is the cause of death to you? can that be good, which is deadly, or the cause of death? or can that be the cause of death which is good? This objection taken out of the mouth of another person proceeds upon a mistake of the apostle's meaning; for though he had said that he died when the commandment came, and found by experience that it was unto death, yet does not give the least intimation that the law was the cause of his death; at most, that it was only an occasion, and that was not given by the law, but taken by sin, which, and not the law, deceived him and slew him. Nor is it any objection to the goodness of the law, that it is a ministration of condemnation and death to sinners; for "lex non damnans, non est lex", a law without a sanction or penalty, which has no power to condemn and punish, is no law, or at least a law of no use and service; nor is the judge, or the sentence which he according to law pronounces upon a malefactor, the cause of his death, but the crime which he is guilty of; and the case is the same here, wherefore the apostle answers to this objection with abhorrence and detestation of fixing any such charge upon the law, as being the cause of death to him, saying,

God forbid;
a way of speaking used by him, as has been observed, when anything is greatly disliked by him, and is far from his thoughts. Moreover, he goes on to open the true end and reason of sin, by the law working death in his conscience;

but sin, that it might appear sin, working death in me by that which
is good;
that is, the vitiosity and corruption of nature, which is designed by sin, took an occasion, "by that which is good", that is, the law, through its prohibition of lust, to work in me all maimer of concupiscence, which brought forth fruit unto death; wherefore, upon the law's entrance into my heart and conscience, I received the sentence of death in myself, that so sin by it, "working death in me, might appear sin" to me, which I never knew before. This end was to be, and is answered by it, yea,

that sin by the commandment might become exceeding sinful;
that the corruption of nature might not only be seen and known to be sin, but exceeding sinful; as being not only contrary to the pure and holy nature of God, but as taking occasion by the pure and holy law of God to exert itself the more, and so appear to be as the words (kay') (uperbolhn amartwlov) , may be rendered, "exceedingly a sinner", or "an exceeding great sinner"; that being the source and parent of all actual sins and transgressions; wherefore not the law, but sin, was the cause of death, which by the law is discovered to be so very sinful.