As Paul continues to make his case for the resurrection, he makes a point that should be self-evident: If Christ rose from the dead, then a Christian cannot say there is no resurrection of the dead, because if they do, they negate their own faith in Christ. It would appear from 15:12 that certain elements in the congregation were saying just that:
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? If there is no resurrection of the dead, then not even Christ has been raised.And if Christ has not been raised, our preaching is useless and so is your faith. 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. (15:12-16)
Yes, it should be self-evident that there either is resurrection or there is not; there is no cherry picking in the matter of resurrection. He continues…
And if Christ has not been raised, your faith is futile; you are still in your sins. Then those also who have fallen asleep in Christ are lost.If only for this life we have hope in Christ, we are of all people most to be pitied. (15:17-19)
To put it in its simplest form, you can’t really be a Christian and deny the resurrection, for denying resurrection of the dead entirely negates being a Christian.

