What does 1 Corinthians 15:16 mean?

This restates the first implication of the idea that Christians will not be resurrected from the dead, even in the end times: If the dead are not raised, then Christ was never raised from the dead. Paul does not allow for the possibility that Christ's resurrection was somehow special and different from the resurrection of those who would believe in Him. Either both resurrections are valid, or neither is.

Paul has already followed that idea to its logical conclusion in one direction—without a resurrected Christ, the gospel is false and all who teach it are lying and all who believe it are deceived. In the following verses, he will explore the implications of worthless faith in a worthless, resurrection-free gospel.

This also reiterates the idea that Christianity is not, and has never been, a blind faith with no connection to either evidence or reason. Scripture itself ties the truth of the gospel to an objective historical claim—something few, if any, other religious faiths would dare attempt.