To understand the necessity of preaching the gospel is to understand the purpose
of preaching it. After Jesus said, "Go ye into all the world and preach the gospel to every
creature," (Mk. 16:15). He gave the purpose for that preaching by adding, "He that
believeth and is baptized shall be saved" (Mk. 16:16). Without the preaching of the gospel,
there can be no salvation.
That is precisely why Paul wrote that the gospel is God's power to save (Rom. 1:16- 17). The gospel is the instrument, or medium, through which God saves men from sin. It is not a medium of condemnation, but of salvation (Jn. 3:17-18), for man stands condemned already because of his sin. The gospel is the culmination of God's great purpose, formed in His eternal counsel before the world began. It is the revelation of His mystery, or plan of salvation for saving us from our sins — not in them.