1 Corinthians 15:29
Else what shall they do which are baptized for the dead, if the dead rise not at all? why are they then baptized for the dead? Else what shall they do which are baptized for the dead, if the dead rise not at all? why are they then baptized for the dead?
The question about those baptized on behalf of the dead belongs to the proof that the dead will be raised in a literal, bodily sense. The surrounding chapter shows that the passage from a mortal to an immortal body does not depend on gathering again the very same particles of matter. What preserves the person through death and resurrection is continuity of organization rather than sameness of material substance. The immortal body is therefore truly the person raised, though not necessarily reconstituted from identical matter.