In 1963 Dr. Merrill C. Tenney published an excellent book titled The Reality of the Resurrection in which he discusses "the essence of the gospel". Although the book is now out of print, it is still available to be read online through Open Library (it's free to sign up and borrow it - just be sure to return it). Why am I excited about this book? Because in contrast to some theologians today, Tenney gets the gospel right! Notice what he says in chapter 4 titled "A DEVELOPING THEOLOGY":
"The cardinal tenets of Christian doctrine which Paul himself illustrated or stressed belonged to the comprehensive body of truth which the church proclaimed. His letters include occasional references to the substance of the message which he preached in pioneer territory. Paul epitomized the substance of his message in his first letter to the Corinthian church. 'For I delivered unto you first of all that which also I received: that Christ died for our sins according to the scriptures; and that he was buried; and that he hath been raised on the third day according to the scriptures; and that he appeared...' (I Cor. 15:3-5a). He concluded this capsule statement with the words 'So we preach, and so ye believed' (15:11). He claimed that his gospel was accepted by the entire church (Gal. 2:6-10) and that there was no distinction between him and the other preachers, except that his ministry was directed chiefly to the Gentiles, whereas theirs was for the Jews."1
Similarly, in chapter 7 titled "THE THEOLOGY OF THE RESURRECTION," Tenney writes:
"Paul, writing to the Galatian churches, stated that Christ gave Himself for our sins that He might free us from this present evil age (Gal. 1:4). He summarized the essence of the gospel for the Corinthian Christians by saying, 'Christ died for our sins according to the scriptures;...he was buried;...he hath been raised on the third day according to the scriptures; and...he appeared...' (I Cor. 15:3-5). The apostle emphasized the theological significance of Christ's death, stating that He 'who knew no sin he [God] made to be sin on our behalf; that we might become the righteousness of God in him' (II Cor. 5:21)."2
Tenney also devotes several pages in his book to discussing the significance of Christ's resurrection from the dead on the third day (Jn. 2:19; Matt. 12:40, 16:21, 17:23, 20:19; Lk. 24:46; Acts 10:40; 1 Cor. 15:4, etc.).3 No-burial gospel advocates ban the truth of the third day from the gospel, but in light of the clear Scriptures on the subject, their belief is truly groundless.4 Tenney affirms that the resurrection of Christ on the third day - like the other elements of the gospel in 1 Corinthians 15:3-5 - is indeed part of "the essence of the gospel".
1 Merrill C. Tenney, The Reality of the Resurrection (New York: Harper and Row Publishers, 1963), pp. 68-69, ellipsis his. (Note: This book was also published by Moody Press, Chicago.)
2 Ibid., p. 154, ellipsis and brackets his, bold added.
3 See chapter 2, "PRE-CHRISTIAN CONCEPTS". (Ibid., pp. 44-46.)