First Corinthians 15 is a great chapter on the resurrection (and rapture) of believers in Christ. In this passage, Paul addresses a wrong notion some of the Corinthian believers had, viz., “some of you say that there is no resurrection of the dead” (1 Corinthians 15:12). One of the apostle’s arguments for the reality of resurrection is the puzzling verse 29: “Now if there is no resurrection, what will those do who are baptized for the dead? If the dead are not raised at all, why are people baptized for them?”
Two things we know for sure about those who were being “baptized for the dead”: these were people familiar to the Corinthians, and their practice of baptism was related to the hope of resurrection. Paul was not referring to pagans conducting a superstitious rite; neither was he giving tacit approval to an unscriptural practice in the Corinthian church.
The best interpretation is that those who were baptized for the dead were true Christian believers who, in coming to faith in Christ, were baptized. They were, in some sense, baptized “for” those who had died. And their baptism bolstered the doctrine of a future resurrection for these reasons:
In the verses immediately following his mention of those who are baptized for the dead, Paul presents an argument from his own testimony: “And as for us, why do we endanger ourselves every hour? I face death every day” (1 Corinthians 15:30–31). Paul and the other apostles obviously had faith in life after death. Otherwise, why would Paul risk his life for the sake of preaching the gospel? In the same way, those who were baptized for the dead were choosing to risk their lives for the hope of the resurrection.
The blood of the martyrs is the seed of the church. This is the truth seen in 1 Corinthians 15:29. As the early Christians fell before their bloodthirsty enemies, others took note. The sight of the believers’ deaths and the intensity of their zeal stirred the hearts of some who decided to also take a stand for Jesus. Rather than shrink back from commitment, the new believers marched forward to join the ranks of Christian soldiers and replace those who had fallen. The brave, newly baptized converts could face death with confidence, because “in Christ all will be made alive” (1 Corinthians 15:22) and “death has been swallowed up in victory” (verse 54).