Why does Paul say that the law came to increase our wrongdoing?

Paul’s statement in Romans 5:20 seems surprising, strange and counter intuitive even.  We expect him to tell us that the Law came to constrain and reduce the impact of sin and wrongdoing by teaching us how to live and by creating sanctions for and deterrents against wrongdoing. However, he insists not just that the Law’s impact was to increase the transgression or trespass but that this was its intent.

If we read a bit further into Romans, we get some clues because in Romans 7, Paul says:

⁷ What then shall we say? That the law is sin? By no means! Yet if it had not been for the law, I would not have known sin. For I would not have known what it is to covet if the law had not said, “You shall not covet.” ⁸ But sin, seizing an opportunity through the commandment, produced in me all kinds of covetousness. For apart from the law, sin lies dead. 

The Law tells us what sin is.  It defines and describes it for us.  This means first that we now know exactly what it means to sin, we cannot claim ignorance.  We knowingly and wilfully choose wrong.  So, the transgression increases because it is now far more serious.

Secondly, Paul tells us that we are faced with a toxic mix, The Law tells us what sin is and sin itself, or our sinful nature takes the opportunity to tempt us, to cultivate a desire for what is forbidden.  We all know how it works, if you are told not to say, touch, taste or think of something, you want to do it all the more.   Note that Paul insists that the Law is not at fault here, rather it is sin that preys on our weakness. However, God gave the Law knowing that this would be the consequence because of our fallen nature, The consequence of the Law being given therefore is not just that it increases the seriousness of our sin but also that we devise more and more ways to sin.  So, there is more sin, it abounds all the more.

This is why in Romans 8, Paul will tell us that

“God has done what the law, weakened by the flesh, could not do. By sending his own Son in the likeness of sinful flesh and for sin,^[c] he condemned sin in the flesh, ⁴ in order that the righteous requirement of the law might be fulfilled in us, who walk not according to the flesh but according to the Spirit.