Schreiner writes (p. 285) on Romans 5.16:

The power of God’s grace is again stressed. The grace given came “after many transgressions”…  The great number of transgressions seems to be a block to God’s grace, but the robustness of grace is such that it triumphs even over a flood of sin (c.f. v. 20).

But the point is not that grace overcomes the many trespasses/transgressions.  Schreiner’s translation on the previous page breaks the parallel structure.  He translates:

And the result of the gift is not like that which resulted from the one who sinned. For the judgment from one sin resulted in condemnation.  But the gift that came after many transgressions resulted in justification.

The NASB is better:

The gift is not like that which came through the one who sinned; for on the one hand the judgment arose from one transgression resulting in condemnation, but on the other hand the free gift arose from many transgressions resulting in justification.

The grace does not come against the trespasses but through them.  The gift arises from the culminating multitude of trespasses just as judgment arose from the first trespass.  No wonder Paul has to state up front that he is not ashamed of this Gospel, and over and over again deal with mockers (“Let us do evil that good may come”).  If the transgressions had not been committed, there would have been no propitiation, nor redemption in Christ Jesus, no condemning sin in His flesh.

Thus, the contrastive conjunction in verse 20 is a bad choice of translation (for both Schriener and the NASB  and the ESV and everyone else.  Here are 20 and 21:

Now the law came in to increase the trespass, and where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord.

This reminds me of something I preached on Romans over a decade ago:

Now Paul goes on to elaborate all this all over again in the rest of chapter 8. And that culminates with his famous list starting in verse 35:

Who shall separate us from the love of Christ? Shall tribulation, or distress, or persecution, or famine, or nakedness, or peril, or sword? Just as it is written, ‘For Thy sake we are being put to death all day long; we were considered as sheep to be slaughtered.’ But in all these things we overwhelmingly conquer through Him who loved us. For I am convinced that neither death, nor life, nor angels, nor principalities, nor things present, nor things to come, nor powers, nor height, nor depth, nor any other created thing shall be able to separate us from the love of God, which is in Christ Jesus our Lord.

Now if you read this as, no matter what happens to us, no matter what we suffer, no matter what trials we experience, still somehow, in some way, we will manage to endure, we will get to Heaven despite all these things, you are not doing justice to Paul’s Gospel.

Jesus didn’t get enthroned beside the Majesty on High despite being born in an animal trough, or despite being rejected by men and misunderstood by his disciples, or despite being betrayed with a kiss, or despite being beaten and tortured, or despite being crucified and killed. No, he attained to glory through these things. He attained to glory by means of tribulation, by means of distress, by means of persecution, by means of famine, nakedness, peril, and sword. He has authoritatively and objectively reinterpreted suffering and death forever. Death is supposed to be the curse for sin and a foretaste of Hell, but He has turned it into the glory road.

Look up at verse 28. Paul doesn’t say that even though many things work together for evil for those who love God nevertheless, by God’s grace they manage to endure these things and inherit glory despite them. No, all things work together for good! All things! Whether death or life or angels or principalities or things present or things to come or height or depth or anything else–all these things work together for good because of the love of God in Christ Jesus our Lord.

So likewise, God brought about the salvation of the world, light to the nations, by Israel’s climactic corporate culmination of apostasy and sin, leading to the crucifixion of Jesus.  “through the Law comes the knowledge of sin”

Here are some notes I scribbled out and published in 2002, for more, but I think there are some typos I never fixed (verse references, maybe)

Note that I labeled this not only “Romans” but “Righteousness of God” because that is what this story reveals, even though many had a problem with it.  It made God seem unrighteous and unfaithful.

PS. Oops.  I forgot to include the rationale for the title.  The common contrast is between Adam and his one sin and Jesus as the New Greater Adam and his one act of righteousness.  But there is another contrast also woven into the story.  There is a contrast between the one trespass of Adam and the many trespasses of the New Adam, Israel.