The sting of death is sin; and the power of sin is the law:
Observe here, 1. Death has its sting. A sting has a threefold property, to pierce, to pain, and to poison: all which were applicable unto death. Observe, 2. Death's sting is sin, or death has its sting upon the account of sin. Sin, like a sting, pierces; it pierces us in its guilt, it pierced Christ in its punishment. The soul which no weapon can reach, sin can wound.
56. The sting of death is sin In other words, “Death has no dart with which to wound us except sin, since death proceeds from the anger of God. Now it is only with our sins that God is angry. Take away sin, therefore, and death will no more be able to harm us.” This agrees with what he said in Romans 6:23, that the wages of sin is death.
If there were no sin, there would be no death. Man's transgression of the law gives death its lawful power. strength of sin is the law--Without the law sin is not perceived or imputed (Rom 3:20; Rom 4:15; Rom 5:13). The law makes sin the more grievous by making God's will the clearer (Rom 7:8-10). Christ's people are no longer "under the law" (Rom 6:14).