Don Carson summarizes an analysis by Greg Gilbert on the different ways the New Testament writers use the word gospel (Gk., εὐαγγέλιον, “good news”):

He argues that some passages where “gospel” is used focus on the message a person must believe to be saved, while others focus on the message that is “the whole good news of Christianity.” (I would prefer to say something like “the whole good news of what God has done in Christ Jesus and in consequence will do.”)

The first list includes, for example, texts like Acts 10:36-43; Romans 1:16-17; 1 Corinthians 1:17-18; 15:1-5—all passages having to do with the forgiveness of sins, how to be saved, how a person is justified, and so forth.

This corresponds to two types of believers who gravitate toward these different foci of the gospel:

In Gilbert’s analysis, one group of believers, whom he designates Group A, rightly argues that “the gospel is the good news that God is reconciling sinners to himself through the substitutionary death of Jesus.”

A second group of believers, whom Gilbert designates Group B, rightly argues that “the gospel is the good news that God is going to renew and remake the whole world through Christ.”

These two groups, he says, tend to talk past one another:

When a Group A believer asks the question What is the gospel? and hears the answer provided by a Group B person, inevitably he or she feels the cross has been lost; when a Group B believer asks the question What is the gospel? and hears the answer provided by a Group A person, inevitably he or she feels the response is too individualistic, too constrained, not driven by the sweep of eschatological expectation and ultimate hope.

Carson insists that these are not two gospels but one gospel in two perspectives:

Gilbert’s point is that although one can discern two foci in “gospel” texts—both having to do with the message of what God has done or is doing, but one more focused on Christ and his cross and how people are saved, the other taking in the broadest sweep of restoration in the new heaven and the new earth—these are not two separate and competing gospels, two distinguishable and complementary gospels. There is but one gospel of Jesus Christ.

The narrower focus draws you to Jesus—his incarnation, his death and resurrection, his session and reign—as that from which all the elements of what God is doing are drawn.

The broader focus sketches in the mighty dimensions of what Christ has secured.

Carson then makes some application:

But this means that if one preaches the gospel in the broader sense without also emphasizing the gospel in the more focused sense of what God has done to bring about such sweeping transformation, one actually sacrifices the gospel.

To preach the gospel as if this were equivalent to preaching, say, the demands of the kingdom or the characteristics and promises of the kingdom, both now in its inauguration and finally in its consummation, without making clear what secures the whole, is not to preach the gospel but only a tired and tiring moralism. Perhaps that is why Paul, talking of what the gospel is, feels free to identify the matters of first importance: Christ crucified and risen again.

This leads to a discussion of the heart of the gospel:

The heart of the gospel is what God has done in Jesus, supremely in his death and resurrection. Period. It is not personal testimony about our repentance; it is not a few words about our faith response; it is not obedience; it is not the cultural mandate or any other mandate. Repentance, faith, and obedience are of course essential, and must be rightly related in the light of Scripture, but they are not the good news.

The gospel is the good news about what God has done. Because of what God has done in Christ Jesus, the gospel necessarily includes the good that has been secured by Christ and his cross work. Thus it has a present and an eschatological dimension. We announce the gospel.

In their book What Is the Mission of the Church? Gilbert and DeYoung say that we could call the broad sense “the gospel of the kingdom”—that is, “the whole complex of promises that God makes to those who are redeemed through Christ. The more narrow sense could be called “the gospel of the cross”—that is, “the message that sinners can be forgiven through repentance and faith in the atoning death and resurrection of Jesus Christ.”

Gilbert and DeYoung summarize some applications and clarifications:

First, there is only one gospel, not two.

Second, the gospel of the kingdom necessarily includes the gospel of the cross.

Third, and more specifically, the gospel of the cross is the fountainhead of the gospel of the kingdom.

They also explain why the NT writers can call “the gospel of the cross” the gospel even while retaining the term for the whole complex of good news.

Because the broader blessings of the gospel are attained only by means of forgiveness through the cross, and because those broader blessings are attained infallibly by means of forgiveness through the cross, it’s entirely appropriate and makes perfect sense for the New Testament writers to call forgiveness through the cross—the fountainhead of and gateway to all the rest—“the gospel.”

That’s also why we never see the New Testament calling any other single promise of God to the redeemed “the gospel.” For example, we never see the promise of the new creation called “the gospel.” Nor do we see reconciliation between humans called “the gospel.” But we do see reconciliation between man and God called “the gospel” precisely because it is the one blessing that leads to all the rest.

When Gilbert and DeYoung state the implications of their analysis negatively, here are three of their summaries of what we should avoid:

  1. It is wrong to say that the gospel is the declaration that the kingdom of God has come. The gospel of the kingdom is the declaration of the kingdom of God together with the means of entering it.
  2. It is wrong to say that the declaration of all the blessings of the kingdom is a dilution of the true gospel.
  3. It is wrong to say that the message of forgiveness of sins through the death and resurrection of Jesus is a reduction of the true gospel.

I recommend Carson’s whole essay as well as the helpful chapter in the DeYoung/Gilbert book.