In an outstanding section of Calvin’s commentary on 2 Corinthians 3.4-11, he makes a great Reformation distinction between the law and the gospel. Here are a few ways he puts it. [The context is, of course, the the old (Mosaic) covenant in comparison to the new covenant. To keep things clear, Calvin is here specifically speaking of the Mosaic covenant (the “ministry of Moses” in his own terms), not the entire OT.]
“True indeed, the grace of God did not, during all that time, lie dormant, but it is enough that it was not a benefit that belonged to the law. For Moses had discharged his office, when he had delivered to the people the doctrine of life, adding threatenings and promises.”
Comparing the law and the gospel, Calvin says, “it is truly and properly affirmed, that the nature of the law is to teach men literally, in such a way that it does not reach farther than the ear; and that, on the other hand, the nature of the gospel is to teach spiritually, because it is the instrument of Christ’s grace.”
The external (“written on stones”) aspect of the law “required to be corrected by the gospel, because it could not but be brittle, so long as it was merely engraven on tables of stone. …From this too, it follows, that the law was the ministry of condemnation and of death; for when men are instructed as to their duty, and hear it declared, that all who do not render satisfaction to the justice of God are cursed, they are convicted, as under sentence of sin and death. From the law, therefore, they derive nothing but a condemnation of this nature, because God there demands what is due to him, and at the same time confers no power to perform it.”
“The law…as it simply prescribes the rule of a good life, does not renew men’s hearts to the obedience of righteousness, and denounces everlasting death upon transgressors, can do nothing but condemn. …The office of the law is to show us the disease, in such away as to show us, at the same time, no hope of cure. …The law leaves man to himself, it condemns him, of necessity, to death.
“The gospel, on the other hand, by which men are regenerated, and are reconciled to God, through the free remission of their sins, is the ministry of righteousness, and, consequently, of life also. …[The gospel is] reckoned the doctrine of life, because it is the instrument of regeneration, and offers to us a free reconciliation with God. …The office of the gospel is to bring a remedy to those who were past hope. …The gospel brings [a man killed by the law] to Christ [and] opens the gate of life” (all emphasis in original).
I also noticed that Matthew Poole made similar comments, and Luther sounded the same notes, of course, in a sermon on the same text.