St. Paul opens his Epistle to the Romans by declaring that he has been “separated unto the gospel [good news] of God” (Rom. 1:1). This agrees with Galatians 1:15,16, where he says:
“It pleased God, who separated me, from my mother’s womb, and called me by His grace, to reveal His Son in me…”
The last book of the Bible tells of the coming “revelation of Jesus Christ” in glory, to judge the world and reign on earth, but here in Galatians we have “the revelation of Jesus Christ” in Paul, the chief of sinners, saved by grace. The salvation of Paul, the one-time leader of the world’s rebellion against Christ, indicated God’s willingness, yes His desire, to save sinners. Thus it was appropriate that God should choose him as the apostle of His grace, making the good news known “to all nations for the obedience of faith.”
Let us not suppose, however, that Paul’s gospel concerned only himself or God’s grace to him. Apart from Christ’s payment for sin at Calvary God could not justly have saved Paul — or any of us. Thus the Apostle goes on, in Romans 1, to explain that this good news which God has sent him to proclaim is “concerning His Son, Jesus Christ our Lord” (1:3).
All through Paul’s epistles he proclaims salvation by grace, on the basis of Christ’s finished work of redemption:
“Being justified freely by His grace, through the redemption that is in Christ Jesus” (Rom. 3:24).
“Who was delivered for our offences and raised again for our justification. Therefore being justified by faith, we have peace with God through our Lord Jesus Christ” (4:25; 5:1).
“Where sin abounded, grace did much more abound, that… grace might reign through righteousness, unto eternal life, by Jesus Christ our Lord” (5:20,21).