If the Bible makes anything clear, it is the fact that the secret of all God’s good news to men is centered in Calvary. It was because Christ was to die for sin that God could proclaim good news to sinners down through the ages.
It was not until some time after the crucifixion, however, that “the preaching of the cross” was widely proclaimed as a message by Paul in “the gospel [good news] of the grace of God” (I Cor. 1:18; Acts 20:24).
The proclamation of “the gospel of the grace of God” was the natural accompaniment to the revelation of the cross as the secret of God’s good news to man. In this proclamation of His over-abounding grace to sinners, everything centers in the cross.
According to Paul’s epistles “we have redemption through His [Christ’s] blood” (Eph. 1:7), we are “justified by His blood” (Rom. 5:9), “reconciled to God by the death of His Son” (Rom. 5:10), “made nigh by the blood of Christ” (Eph. 2:13), and “made the righteousness of God in Him” because “God hath made Him to be sin for us” (II Cor. 5:21).
The “covenant” of the Law was abolished by the cross (Col. 2:14), the curse of the Law was removed by the cross (Gal. 3:13), the “middle wall of partition” was broken down by the cross (Eph. 2:14,15), and believers in Christ are “reconciled to God in one body by the cross” (Eph. 2:16). Little wonder Paul calls this message “the preaching of the cross”!
To the believers it is thrilling indeed, and how thankful we should be, to see the cross as God’s reply to Satan when, at first glance, it had appeared that the cross was Satan’s greatest triumph. source