In this brief verse we find a summary of the doctrine of sin, death, and the law.
It is sin that gives to death its power, since originally death was God’s punishment for sin. But once sin is dealt with, then death is no longer a punishment and therefore no longer to be feared. Death is now an entrance into eternal life.
If death is a scorpion and sin its sting, then the law (that is, the law of God) is what gives the sting its deadly power. Paul does not stop to explain this statement, as he has undoubtedly instructed the Corinthians in the doctrine of sin, death, and the law before. In his letter to the Romans, however, we find a lengthy discussion of the connection between sin and the law.
The law declares us guilty of sin (Romans 5:13). Moreover, the law awakens our desire to sin (Romans 5:20; Romans 7:5, Romans 7:8). The law is good, but it has no power in itself to make us good. It exposes us for who we are: sinners.
56 The sting of death is sin, and the power of sin is the law.