1 Corinthians 15:12

Having confirmed the truth of our Saviour's resurrection, the apostle goes on to refute those among the Corinthians who said there would be none: If Christ be preached that he rose from the dead, how say some among you that there is no resurrection of the dead? Co1 15:12. It seems from this passage, and the course of the argument, there were some among the Corinthians who thought the resurrection an impossibility. This was a common sentiment among the heathens. But against this the apostle produces an incontestable fact, namely, the resurrection of Christ; and he goes on to argue against them from the absurdities that must follow from their principle. As, I. If there be (can be) no resurrection of the dead, then Christ has not risen (Co1 15:13); and again, "If the dead rise not, cannot be raised or recovered to life, then is Christ not raised, Co1 15:16. And yet it was foretold in ancient prophecies that he should rise; and it has been proved by multitudes of eye-witnesses that he had risen. And will you say, will any among you dare to say, that is not, cannot be, which God long ago said should be, and which is now undoubted matter of fact?" II. It would follow hereupon that the preaching and faith of the gospel would be vain: If Christ be not risen, then is our preaching vain, and your faith vain, Co1 15:14.

— Matthew Henry's Concise Commentary (public domain)

if--Seeing that it is an admitted fact that Christ is announced by us eye-witnesses as having risen from the dead, how is it that some of you deny that which is a necessary consequence of Christ's resurrection, namely, the general resurrection? some--Gentile reasoners (Act 17:32; Act 26:8) who would not believe it because they did not see "how" it could be (Co1 15:35-36).

— Jamieson-Fausset-Brown Commentary (public domain)