“Throughout the narratives of Exodus 19-Deuteronomy there are numerous examples of Israel’s failure to follow God’s will. Here we can see the hand of the author at work. After each episode of disobedience we can see that God gave Israel a new and more complete set of laws.
As Israel continued to transgress the laws given to them, God continued to give them more. God did not give up on His people. When they sinned, he added laws to keep them from sinning further.
The laws were not added to keep them from sinning; the laws were added to keep them from disappearing into the world of sin around them. It thus was the transgressions of the people that provided the motivation for God’s giving the Mosaic law.
As the transgressions increased, more laws were added.”
–John H. Sailhamer, The Meaning of the Pentateuch (Downers Grove, IL: InterVarsity, 2009), 561.
I don’t follow Sailhamer here. Paul has a different take in Romans 5:20 –
Romans 5:20: Now the law came in to increase the trespass, but where sin increased, grace abounded all the more,
Paul also said, “Why then the law? It was added because of transgressions” (Gal 3.19). So it seems two things are going on, and Sailhamer is properly emphasizing the Galatians angle, that the law didn’t negate the promises to the fathers, but in fact was added to protect and guard them until Messiah came. Romans 5:20, also speaks about the law as coming in alongside (it’s a rare Greek word for “came”). So it’s similar to Galatians, speaking of the law being added to, but not overtaking the promises.
So what does it mean to “multiply the trespass”? Does it mean to cause someone to sin? Well, no. Then the law wouldn’t be holy. Romans 7 helps us some here, “I would not have known sin if it were not for the law” (7.7).
Sailhamer is saying that the intention of the law for the divine perspective is to keep people from sinning further. What happened is that the people were hard-heartened and rebellious, and rather than listening to God, continued to sin and when new laws came, sinned further.
If you can’t follow Sailhamer here, I don’t see how you can follow Paul between Romans 5:20 and Galatians 3:19.
Rom. 5:20 “the trespass” is actually referencing the sin of Jesus murder. In Gal. 3:19 “trespasses” is used relative to the fact that all of the written code was violated by murdering Jesus Christ.
The block buster for substitutionary atonement is Rom. 2:13. What Paul has intentionally done by writing Romans is to kick substitutionary atonement in the head.
“For it is not those who hear the law who are righteous in God’s sight, but it is those who obey the law who will be declared righteous.” Rom. 2:13 The law he is referencing is not the OT written code rather he is referencing the law that has been added. See Heb. 7:12 “change also of the law.” The murder of Jesus Christ became an accountable sin for us so that we might become the righteousness of God by the faith of obeying only the law REPENT. No man’s murder can be a direct benefit.