Yes, the Gospel is in the Gospels, but there is a clear shift in the meaning of “Gospel” as we progress from the “Gospels” (Matthew, Mark, Luke and John), to the epistles, particularly those written by Paul the Apostle.
The word “gospel” is used several times throughout Matthew, Mark and Luke (not in John). It essentially means “good tidings”, or “good news”, and usually refers to the good news that the Messiah has come, the Savior, the King and His Kingdom in some sense. And it certainly was Good News.
But there is much about the Gospel, as it is presented in the epistles, that is lacking in the Gospels. Why? Primarily because Jesus Himself lived on earth under the Old Covenant. Much of what He taught, He taught to Jews who were still under the Law of the Old Covenant. He was in a transition time, to be sure. He was beginning to herald something glorious beyond the Law. But He still had to live under the Law, in order to fulfill it, and be qualified as the perfect Lamb of God.
There were seeds of grace in His ministry. But those seeds had been planted even in Genesis, with the promise of the crushing of the head of the serpent. And in Jeremiah Chapter 31, where the New Covenant was promised.
The Gospel of the New Covenant, as it was expounded by Paul, for example, included not only a general faith in Jesus Christ as Lord, but faith in a complete Messiah and His work on the cross, and His resurrection. Even John wrote, “but these have been written so that you may believe that Jesus is the Christ, the Son of God; and that believing you may have life in His name.” (John 20:31) And this was in the only Gospel that didn’t contain the word “gospel”. But it lifts Him up, the Lord Jesus Christ, and calls us to believe in Him as Lord, and Savior.
Probably the clearest factual presentation of the Gospel content is in 1 Corinthians 15:1-4, where it says,
“Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain. For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures…”
There is a principle of hermeneutics (Bible interpretation) that says that, all things being equal, Scripture tends to progressively shed more light on a given subject as we progress through the Bible. And sure enough, the gospel is really explained in all its glory in the epistles, not in the Gospels.
In fact, much of what Jesus taught seems to smack of legalism. And why not? He was teaching under the Old Covenant, which later was to become “obsolete” (Hebrews 8). There was some legalism, but it was righteous legalism, true and Biblical legalism.
My point is this. It is a mistake to go back to the Gospels to explain that Gospel of Grace which is so exalted in Romans and Galatians. It is a mistake, and leads to confusion, to proclaim “The Gospel According To Jesus”. We are not saved under the New Covenant by “give all that you are for all that He is”. First, that would be salvation by works as a reward, and second, it’s a good thing that giving “all that you are” is not the condition for salvation, since I’m confident that no one has ever given all that he is. We are not saved under the New Covenant by “deny yourself, take up your cross, and follow Me” (Matthew 16:24). That “follow me” is in the present tense, and involves the linear action of a whole life of discipleship. But the Gospel of Grace says that “he who has the Son has life” now (1 John 5:12).
And out of that new life springs fruit. But the fruit comes from the life, not vice versa.