For my daily Greek reading I was in 1 Corinthians 15 this morning. The opening paragraph is very helpful in orienting us to the primacy of the gospel:
“ 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,  and that He appeared to Cephas, then to the twelve.  After that He appeared to more than five hundred brethren at one time, most of whom remain until now, but some have fallen asleep;  then He appeared to James, then to all the apostles;  and last of all, as to one untimely born, He appeared to me also.  For I am the least of the apostles, and not fit to be called an apostle, because I persecuted the church of God.  But by the grace of God I am what I am, and His grace toward me did not prove vain; but I labored even more than all of them, yet not I, but the grace of God with me.  Whether then it was I or they, so we preach and so you believed.  Now if Christ is preached, that He has been raised from the dead, how do some among you say that there is no resurrection of the dead?  But if there is no resurrection of the dead, not even Christ has been raised;  and if Christ has not been raised, then our preaching is vain, your faith also is vain.  Moreover we are even found to be false witnesses of God, because we testified against God that He raised Christ, whom He did not raise, if in fact the dead are not raised.  For if the dead are not raised, not even Christ has been raised;  and if Christ has not been raised, your faith is worthless; you are still in your sins.  Then those also who have fallen asleep in Christ have perished.  If we have hoped in Christ in this life only, we are of all men most to be pitied.” (NASB)
Several things stand out:
First, Paul makes it clear that the gospel is “of first importance,” literally, “among the first (i.e., most important) things” (ἐν πρώτοις, cp. BDAG). This implies that there are many other important issues in the Christian faith and life — perhaps some of the topics Paul has addressed in the foregoing parts of his first letter to the Corinthians, e.g., church unity, church discipline, the dangers of immorality, lawsuits, marriage and divorce, food sacrificed to idols, and spiritual gifts — but none of these stands on the same level as the gospel itself.
Second, this begs the question, “What is the gospel?” Paul answers the question by pointing to the central reality of substitutionary atonement (”that Christ died for our sins”), as well as his burial and resurrection on the third day, confirming that his sacrifice of atonement had been accepted. The prepositional phrase in the death-formula, ”for our sins” (ὑπὲρ τῶν ἁμαρτιῶν), is critical, because it identifies the death of Christ as a penal substitution. That is, he died the death that we deserved for our sins. [See Wallace, Greek Grammar Beyond the Basics, pp. 383-89, on the substitutionary meaning of the preposition ὑπέρ in Koine Greek.]
Third, the death of Christ for our sins and his resurrection on the third day is also the content of a message that is proclaimed. Paul uses several different verbs to refer to the proclamation of the gospel message concerning the death and resurrection of Christ: twice, the verb εὐαγγελίζομαι (”to preach the gospel,” vv 1-2); twice, the language of “handing on” and “receiving” a tradition (vv 1, 3); twice, the verb κηρύσσω (”to herald, proclaim,” vv 11, 12); once, its cognate noun τὸ κήρυγμα (v 14); and once, the verb μαρτυρέω (”to bear witness,” v 15). The gospel, then, is the apostolic preaching of the saving message of the cross of Christ. Now that the apostles have died, we merely preach what the apostles preached, but we do so in their name and authority.
Fourth, the message is not only proclaimed, it is also believed, and when it is believed, received, and held fast, it leads to salvation. This is stated at the beginning of the passage: “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” (vv 1-2). What it means to be “saved” is fleshed out a bit later: “For if the dead are not raised, not even Christ has been raised; and if Christ has not been raised, your faith is worthless; you are still in your sins. Then those also who have fallen asleep in Christ have perished. If we have hoped in Christ in this life only, we are of all men most to be pitied.” The point of believing that Jesus died for our sins and rose again is that we will not perish or die in our sins, but will have the hope of attaining to the resurrection from the dead, of which Christ’s resurrection is the pledge.
Note the tie between the message and faith: “So we preached and so you believed” (v 11). Thus the message is preached, then it is received in faith, and the result is that when we die, we do not perish, but are destined to attain resurrection life with Jesus at his coming. This is why Paul mentions the fact that some of the witnesses of the resurrection of Jesus have fallen asleep (v 6) — they did not merely hope in Christ in this life only (v 19). Their hope is that, through the death of Christ for their sins, they will be raised up with Christ in the age to come.
So what’s the point?
This, I believe, is a most helpful passage in orienting us to what is primary for Paul, and by implication, what ought to be primary for us as well. When people read our books and blogs, or listen to our sermons, or attend our worship services, what do they perceive is “of primary importance” to us? I hope it is not that we are “Reformed,” or that we subscribe to “the Reformed Confessions,” or that we are “Presbyterian” in our church government. I hope it is that we love, preach, and live out of the apostolic gospel of Christ’s death for our sins.
This is also relevant for us in helping us to decide what our relationship ought to be with broader evangelicalism, and indeed with all professing Christians. They may be confused about many matters. They may have a low view of the church and the sacraments. They may be too quick to reject the traditions and creeds of the church. They may hold to something less than a purely monergistic soteriology. They may think baptism must be preceded by a profession of faith. But if they have received, stand firm in, and preach this gospel, then they are to be received as brothers in Christ and to be encouraged to continue in the gospel, even as we also discuss other matters with them (just as Paul does in his letters to the Corinthians). This is why I am much more concerned about those so-called evangelicals who are denying penal substitution, than I am about evangelicals who disagree with me on infant baptism, for example.
Of course, I realize that there are other essentials not addressed by Paul in this immediate paragraph, such as Christology and justification by faith alone, that must also be taken into account. These should also be understood as presupposed and can be fleshed out by other NT passages. My point is that the saving work of Christ on the cross was central to Paul’s preaching and that this ought to inform our priorities today as well.