John Chrysostom

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 offences that an indemnity was brought about. How is this plain? …

Homily on Romans X ↗

Theophylact of Ohrid

For the "transgression," that is, the sin subject to condemnation, proceeding from Adam, led "to condemnation," that is, to death, and a multitude of sins always existed among his descendants, so that people were in the power of many sins and death. "But the gift of grace is unto justification from many transgressions," that is, grace not only blotted out that one sin, but also the other sins that followed after it; for it became our justification, granting us forgiveness of all transgressions committed after the fall.

Commentary on Romans ↗

Thomas Aquinas

Then when he says, and not as it was, he compares Christ's grace to Adam's sin as regards the effect, because not only does each affect many, but Christ's grace had a greater effect than Adam's sin. And concerning this he does three things. First, he states his proposition; second, he clarifies it, at for judgment indeed; third, he proves it, at for if by one man's offense. First, therefore, he says: not only does Christ's grace more abound for many than Adam's sin, but it produces a greater effect in them. …

Commentary on Romans ↗