The Gospel in Brief
The entire New Testament makes it clear that the gospel message demands a response of faith and offers salvation and eternal life to all who do believe (Romans 1:16; Ephesians 1:13). In very simple terms, the gospel is the good news of how full redemption from sin has been accomplished solely through the atoning work of Christ, and how it can be applied to sinners (2 Timothy 1:10).
But what are the essential facts and doctrines that make up the gospel message?
The apostle Paul summarized the gospel succinctly in 1 Corinthians 15:1-4. That passage is an outline only and not an exhaustive treatise on the gospel, but it is perhaps the best starting place in all the New Testament to get a concise overview of what the gospel message consists of.
Notice that Paul makes it clear both here and elsewhere that a correct understanding (and proclamation) of the gospel includes not only the historical facts of Christ's death, burial and resurrection but also the true meaning of those events "according to the Scriptures."
So even though some might suggest that Paul's shorthand gospel outline omits certain other doctrines Christians generally regard as fundamental precepts of gospel truth (such as Christ's deity and incarnation—or the authority and inspiration of the Scriptures), those things are necessary presuppositions of the facts Paul does list. Those and many other truths are included implicitly in the words "according to the Scriptures."
Jesus' death, for example, is essential to a right understanding of what Paul means by "Christ." The priniciples of substitutionary atonement and justification by faith permeated all of Paul's teaching and consumed his energies when he wrote in defense of the gospel, so that there's no doubt he regarded those truths as utterly non-negotiable, too.
It would be a serious mistake to conclude that because he omitted explicit mention of those points in this summary, he must have regarded them as extraneous to the gospel message. They are clearly assumed and subsumed in the statement "Christ died for our sins."
Remember, Paul condemned the Galatian false teachers for proclaiming a different gospel (Galatians 1:8-9), even though nothing suggests they ever disputed any of the historical facts Paul gives in 1 Corinthians 15.
Instead, their error related to the question of whether obedience to the law was instrumental in justification (Galatians 2:16). That, Paul said, is a fatal corruption of the gospel.
--Phil Johnson, Executive Diretor of 'Grace to You'