Romans 5
20 Moreover the law entered that the offense might abound. But where sin abounded, grace abounded much more, 21 so that as sin reigned in death, even so grace might reign through righteousness to eternal life through Jesus Christ our Lord.

Commentary:
a. The law entered that the offense might abound: Paul has shown us that the law does not justify us. Now he shows that in itself, the law doesn’t even make us sinners – Adam did that. Then what purpose does the law serve? There is a clear purpose for the law and part of it is so that the offense might abound. The law makes man’s sin clearer and greater by clearly contrasting it with God’s holy standard.

i. The flaws in a precious stone abound when contrasted with a perfect stone or when put against a contrasting backdrop. God’s perfect law exposes our flaws, and makes our sin abound.

It is interesting that Paul clearly points out that we were made sinners, and THEN the law came about.