16 And not as it was by one that sinned, so is the gift: for the judgment was by one to condemnation, but the free gift is of many offences unto justification.
There is an obvious difference between the fact that those who have sinned in imitation of Adam’s transgression have been condemned and the fact that the grace of God in Christ has justified men not from one trespass but from many sins, giving them forgiveness of sins.
Paul wants to say that it was because of Adam’s sin, although it was only one, that God condemned many, on account of the fact that they copied Adam. But the grace of the Lord was measured not according to that one sin but according to the many sins which all had committed. Thus Christ transformed many sins into righteousness.
And what is this that he is speaking of? It is that sin had power to bring in death and condemnation; but grace did not do away that one sin only, but also those that followed after in its train. Lest then the words "as" and "so" might seem to make the measure of the blessings and the evils equal, and that you might not think, upon hearing of Adam, that it was only that sin which he had brought in which was done away with, he says that it was from many offenses that an indemnity was brought about. How is this plain? Because after the numberless sins committed after that in paradise, the matter issued in justification. But where righteousness is, there of necessity follows by all means life, and the countless blessings, as does death where sin was. For righteousness is more than life, since it is even the root of life. That there were several goods then brought in, and that it was not that sin only that was taken away, but all the rest along with it, he points out when he says, that "the gift was of many offenses unto justification." In which a proof is necessarily included, that death was also torn up by the roots. But since he had said, that the second was greater than the first, he is obliged to give further grounds again for this same thing. For, before, he had said that if one man's sin slew all, much more will the grace of One have the power to save. After that he shows that it was not that sin only that was done away by the grace, but all the rest too, and that it was not that the sins were done away only, but that righteousness was given. And Christ did not merely do the same amount of good that Adam did of harm, but far more and greater good. Since then he had made such declarations as these, he wants again here also further confirmation of these. And how does he give this confirmation? He says, (Romans 5:17)
The free gift is much greater than the judgment.… For it was not just Adam’s sin which was done away with by the free gift but all other sins as well. And it was not just that sin was done away with—justification was given, too. So Christ did not merely do the same amount of good that Adam did of harm, but far more and greater good.
The effect of the gift is greater than that of the sin. From the sin of one righteous man came the judgment of death. Adam never came across all the righteousness which he destroyed, but Christ discharged the sins of many by his grace. Adam was only the model for sin, but Christ both forgave sins freely and gave an example of righteousness.
There is one great difference between Adam’s sin and God’s gift in Christ. Adam’s sin brought punishment on all those who came after him, and so they died. But the free gift is different. For not only did it take effect in the case of those who came afterward; it also took away the sins of those who had gone before. It is therefore much greater, because where sin harmed those who came after, grace rescued not only those who came after but those who had transgressed before as well.
[AD 384] Ambrosiaster on Romans 5:16