A friend asks: “Have you heard the good news?” and you reply: “What good news?” Naturally! All good news is not the same. Yet few people follow this procedure when they read in the Bible the phrase “the gospel” — which simply means “the good news.” They have been taught that “the gospel is the gospel” and “there is only one gospel,” but this is simply not so in the light of the Bible itself.
God has not proclaimed only one gospel, one item of good news, down through the ages, but many. And He has qualified the word “gospel” by distinctive titles. The “gospel of the kingdom” and the “gospel of the grace of God” are not the same, and certainly the “gospel of the circumcision” and the “gospel of the uncircumcision” are not the same.
When we come upon the phrase “the gospel” without any qualifying title, we should immediately ask: “Which gospel?” and invariably the context will provide the answer. Luke 9:6, for example, simply states that the twelve disciples went about “preaching the gospel,” but Verse 2 of the same chapter explains how the Lord had sent them “to preach the kingdom of God” — not the cross, but the kingdom, since He, the King, was in their midst. These disciples could not have engaged in “the preaching of the cross,” as Paul later did, for it was not until at least two years later that the Lord “began” to tell them how He must suffer and die (Matt. 16:21) and Peter “began to rebuke Him” (Ver. 22) and none of the twelve even understood what He was talking about (Luke 18:34).
But whereas “the gospel of the kingdom” had been committed to the twelve while Christ was on earth, “the preaching of the cross” (as good news) and “the gospel of the grace of God” was later committed to the Apostle Paul and to us (1 Cor. 1:18; Acts 20:24).
Today we do not proclaim the kingdom rights of Christ. Rather we proclaim “redemption through His blood, the forgiveness of sins, according to the riches of His grace” (Eph. 1:7). source