Why do we call the Gospel Peter preached the “Kingdom Gospel” and the Gospel Paul preached the “Gospel of the Grace of God” or “Grace Gospel?” The primary emphasis of Peter’s Gospel was obedience to God’s Law “by works” so He would send Christ to earth to set up His earthly Messianic Kingdom. The Grace Gospel emphasizes a Mystery known only to God before He revealed it to Paul. That Mystery is that Christ would dwell in the hearts and lives of Gentiles and Jews “by grace through faith” and build them into a unified Spiritual Body. Peter preached Christ reigning on earth from a King’s throne in Jerusalem. Paul preached Christ reigning in the lives of Gentiles and Jews from a throne in their hearts. Peter’s Gospel is about fulfilling Old Testament prophecy about Israel. Paul’s Gospel is about fulfilling the Mystery of God that was hidden in God from “before the creation of the world.” Some even call the present administration “The Dispensation of the Mystery.”
What’s a “Mystery?” The Greek word is musterion. It translates as “mystery,” “secret” or “deep truth.” Here’s how Paul used the word to teach Christ’s followers in the “Dispensation of Grace” what God had for them. I’ve emphasized the English words used to translate musterion.
“And he made known to us the mystery of his will according to his good pleasure, which he purposed in Christ, to be put into effect when the times will have reached their fulfillment–to bring all things in heaven and on earth together under one head, even Christ.” (Ephesians 1:9-10)
“Surely you have heard about the administration of God’s grace that was given to me for you, that is, the mystery made known to me by revelation, as I have already written briefly. In reading this, then, you will be able to understand my insight into the mystery of Christ, which was not made known to men in other generations as it has now been revealed by the Spirit to God’s holy apostles and prophets. This mystery is that through the gospel the Gentiles are heirs together with Israel, members together of one body, and sharers together in the promise in Christ Jesus. I became a servant of this gospel by the gift of God’s grace given me through the working of his power. Although I am less than the least of all God’s people, this grace was given me: to preach to the Gentiles the unsearchable riches of Christ, and to make plain to everyone the administration of thismystery, which for ages past was kept hidden in God, who created all things.” (Ephesians 3:2-9)
“This is a profound mystery–but I am talking about Christ and the church.” (Ephesians 5:32)
“I have become its servant by the commission God gave me to present to you, the word of God in its fullness–the mystery that has been kept hidden for ages and generations, but is now disclosed to the saints. To them God has chosen to make known among the Gentiles the glorious riches of this mystery, which is Christ in you, the hope of glory.” (Colossians 1:26-27)
“My purpose is that they may be encouraged in heart and united in love, so that they may have the full riches of complete understanding, in order that they may know themystery of God, namely, Christ, in whom are hidden all the treasures of wisdom and knowledge.” (Colossians 2:2-3)
“Devote yourselves to prayer, being watchful and thankful, And pray for us, too, that God may open a door for our message, so that we may proclaim the mystery of Christ, for which I am in chains.” (Colossians 4:3)
“Beyond all question, the mystery of godliness is great: He appeared in a body, was vindicated by the Spirit, was seen by angels, was preached among the nations, was believed on in the world, was taken up in glory.” (1 Timothy 3:16)
“We do, however, speak a message of wisdom among the mature, but not the wisdom of this age or of the rulers of this age, who are coming to nothing. No, we speak of God’ssecret wisdom, a wisdom that has been hidden and God destined for our glory before time began.” (1 Corinthians 2:6-7)
“So then, men ought to regard us as servants of Christ and as those entrusted with the secret things of God.” (1 Corinthians 4:1)
“They must keep hold of the deep truths of the faith with a clear conscience.” (1 Timothy 3:9)