1Co 15:1 Now, brothers, I want to remind you of the gospel I preached to you, which you received and on which you have taken your stand. 2 By this gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain.
1Co 15:3 For what I received I passed on to you as of first importance : that Christ died for our sins according to the Scriptures, 4 that he was buried, that he was raised on the third day according to the Scriptures, 5 and that he appeared to Peter, and then to the Twelve. 6 After that, he appeared to more than five hundred of the brothers at the same time, most of whom are still living, though some have fallen asleep. 7 Then he appeared to James, then to all the apostles, 8 and last of all he appeared to me also, as to one abnormally born.
1Co 15:9 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. 10 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. 11 Whether, then, it was I or they, this is what we preach, and this is what you believed.
1Co 15:12 But if it is preached that Christ has been raised from the dead, how can some of you say that there is no resurrection of the dead? 13 If there is no resurrection of the dead, then not even Christ has been raised. 14 And if Christ has not been raised, our preaching is useless and so is your faith. 15 More than that, we are then found to be false witnesses about God, for we have testified about God that he raised Christ from the dead. But he did not raise him if in fact the dead are not raised. 16 For if the dead are not raised, then Christ has not been raised either. 17 And if Christ has not been raised, your faith is futile; you are still in your sins.18 Then those also who have fallen asleep in Christ are lost. 19 If only for this life we have hope in Christ, we are to be pitied more than all men.
1Co 15:20 But Christ has indeed been raised from the dead, the firstfruits of those who have fallen asleep. 21 For since death came through a man, the resurrection of the dead comes also through a man. 22 For as in Adam all die, so in Christ all will be made alive. 23 But each in his own turn: Christ, the firstfruits; then, when he comes, those who belong to him. 24 Then the end will come, when he hands over the kingdom to God the Father after he has destroyed all dominion, authority and power. 25 For he must reign until he has put all his enemies under his feet. 26 The last enemy to be destroyed is death. 27 For he “has put everything under his feet.” Now when it says that “everything” has been put under him, it is clear that this does not include God himself, who put everything under Christ. 28 When he has done this, then the Son himself will be made subject to him who put everything under him, so that God may be all in all. And if Christ has not been raised, your faith is futile; you are still in your sins.
-- First Corinthians 5:1-28 (NIV)
Paul gave the Corinthians a crystal clear choice here: Either there is resurrection or there isn't. And if there isn't, then nothing Paul or the Apostles have already said or will say in the future can provide the hope that we have in Jesus Christ. We remain in our sins. We have been lied to.
But, if Jesus DID rise from the dead as the witnesses reported, then the preaching of those witnesses (and Paul, whose epiphany was years after the Resurrection) is valid, and they speak with the authority of those who have been called by the Lord to preach the Gospel to everyone.
It all hinges on the Resurrection. and far too many of the original witnesses to that event died for believing and preaching the Good News, for me to blow it off as delusion or hoax. I have seen too many changed lives to casually deny the Lord's work in the world today.
Christ is Risen!