“Now, brothers and sisters, I want to remind you of the gospel I preached to you, which you received and on which you have taken your stand. By this gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain.
For what I received I passed on to you as of first importance: that Christ died for our sins according to the Scriptures, that he was buried, that he was raised on the third day according to the Scriptures, and that he appeared to Cephas, and then to the Twelve. After that, he appeared to more than five hundred of the brothers and sisters at the same time, most of whom are still living, though some have fallen asleep. Then he appeared to James, then to all the apostles, and last of all he appeared to me also, as to one abnormally born.
For I am the least of the apostles and do not even deserve 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 to me was not without effect. No, I worked harder than all of them—yet not I, but the grace of God that was with me. Whether, then, it is I or they, this is what we preach, and this is what you believed.”
“This is what we preach, and this is what you believed,” Paul writes. How profoundly simple the Gospel is! The area of first concern, seen here, is that our sins needed a sacrifice, for which Christ paid with His life and was buried, being raised on the third day according to the Scriptures, then appeared to Cephas [Peter] and the Twelve and to more than five hundred at the same time. Elsewhere, Paul wrote to the Romans that “the message concerning faith that we proclaim: If you declare with your mouth, ‘Jesus is Lord,’ and believe in your heart that God raised him from the dead, you will be saved. For it is with your heart that you believe and are justified, and it is with your mouth that you profess your faith and are saved” (Rm. 10:8-10). How are we to expound on this?
First, the necessity: we have all sinned and fall short of the glory of God (Rm. 3:23). Man is eternally separated from God because of this sin. We have all missed the mark and are equally yoked with the burden of the impending judgment and following condemnation of eternal separation from our holy God in hell, where there will be “weeping and gnashing of teeth” (Mt. 5:29-30; 8:12; 10:28; 13:42, 50). For man’s sinfulness, though, Christ Jesus came as the sole reconciliation of man to his Maker (Jn. 14:6). While we were yet sinners, Christ died for us and “since we have now been justified by his blood, how much more shall we be saved from God’s wrath through him! For if, while we were God’s enemies, we were reconciled to him through the death of his Son, how much more, having been reconciled, shall we be saved through his life” (Rm. 5:1-11)! Pertaining to confession and belief, writes Paul, this was of first importance, for it is this which we confess with mouths when we declare “Jesus is Lord” and believe in our hearts regarding the resurrection of our Lord on the third day. Next, Paul validates the necessary with what could be easily attested: Christ appears to the Apostles and more than five-hundred others, most of whom were still alive at the time the local congregation received the letter. Not only does he present it as believable, but also sustainable against naysayers, validating it with supporting evidence that could be investigated.
By using the term “Christ,” he adds to the necessity of Jesus in the act of reconciliation. “Christ,” being another way to write or say “Messiah” meaning “a person invested by God with special powers and functions who is described as ‘the priest that is anointed.’” According to The Oxford Dictionary of the Christian Church, “it was however used more particularly of the king, who was conceived as anointed by Divine command.” What we derive from this understanding of the term “Messiah” is that reconciliation between God and man could have only happened through Jesus.
What does all of this bring us to? Jesus, being the Christ or Messiah, was the only one who could have paid the price of our sins, presenting a sweet smelling sacrifice to the Father, and He did so by dying on the cross to save wicked man, after which He was buried and rose again on the third day. He then appeared to more than five hundred, outside of the Apostles, most of which were still alive at the time of the letter’s composition. This is of first importance regarding what we believe and confess, as well as what we exhort others to believe, declaring that “Jesus is Lord” and believing in their hearts that God raised Him from the dead on the third day, according to the Scripture. How delightfully simple, but deeply profound indeed!
Gloria in Excelsis Deo.
 Cross, F. L., & Livingstone, E. A. (2005). The Oxford dictionary of the Christian Church (3rd ed. rev.) (1082). Oxford; New York: Oxford University Press.