It may be helpful to think of the gospel in terms of its essence and the fullness. On one hand, one can distil the gospel to its essential core. We may not say it exactly the same (every time). But the essential elements would always be there. That is why Paul could write 1 Corinthians 15:1-8, a clear statement of his essential message. That complements nicely Jesus words recorded in Luke 24:45-49 (see below.)
But there is a fullness to the gospel, as well. Its truths, themes and implications are so vast that it would take a lifetime to explore. Indeed, we never master the gospel and move on (to some other truth). It is not merely the initial message for the follower of Christ, it is the only message. We are gospel people. And so, we dig deeper and deeper and become richer and richer, always growing in our understanding. For an analogy, think of a gold mine. The deeper you go, the richer you become, not because you are mining something different. Rather you are simply getting more of the same pure gold. Matthew, Mark, Luke and John are more full (and narrative) presentations of the same gospel truth as Paul proclaimed. The book of Romans is all gospel truth, unpacked in its theological implications (as is Galatians and the other epistles.) Jesus enabled the disciples to see that the Law of Moses, the prophets and the Psalms (the OT Scriptures) all spoke of him (that is, gospel truth.) The Bible, from beginning to end, is gospel truth!
While I don’t want to press this too far, I would suggest that it is our understanding of the essence of the gospel that enables us to communicate accurately, while it is our growing understanding of the fullness of the gospel that enables us to communicate relevantly. We get the message right if we understand the essence, but we can share that in a wide array of effective ways with its fullness. Thus you can tell the story of redemption (the biblical storyline), or you can explain the gospel thematically (perhaps the theme of the promise of the Spirit – Acts 2 – or using Steps to Peace with God – Billy Graham). You may share it testimonially (as the Samaritan woman) or theologically (as Paul does in Romans. Think of how many have come to faith simply reading the truths of Romans.) It remains the same essence and but the audience or communication context determines what form of presentation is most appropriate.
So what is the essence? Compare Jesus’ summary statement in Luke 24:45-49 with Paul’s in 1 Corinthians 15:1-8. There are common elements:
- Who is Jesus: The Christ
- What has he done: Died and rose again.
- Why: Forgiveness of sins
- How do we know: OT Scriptures and resurrection appearances
- How are we to respond: Repentance (Luke) and Faith (Paul)
If this is accurate, then our witness is always who is Jesus, what he has done and why. But we have an unending array of possibilities as to how we can accurately and relevantly communicate and apply this gospel.