"For until the law, sin was in the world; but sin is not imputed when there is not law."
What does that big word "imputed" mean? I found it helpful to see another verse about sin and the law. "The sting of death is sin; and the strength of sin is the law." (1 Corinthians 15:56). It is because of the law that we know what sin is - in fact, the law is considered our school-master: "Wherefore the law was our schoolmaster to bring us unto Christ, that we might be justified by faith." (Galatians 3:24) Because we have broken God's law, we were slaves under the law . . . until . . . God gave His son Jesus and sent the free gift of salvation (see Romans 5:15)! We can repeat with David, "Blessed is the man unto whom the LORD imputeth not iniquity, and in whose spirit there is no guile." (Psalm 32:2)