5. (1Co 15:29-32) More reasons to believe in the principle of resurrection.
Otherwise, what will they do who are baptized for the dead, if the dead do not rise at all? Why then are they baptized for the dead? And why do we stand in jeopardy every hour? I affirm, by the boasting in you which I have in Christ Jesus our Lord, I die daily. If, in the manner of men, I have fought with beasts at Ephesus, what advantage is it to me? If the dead do not rise, "Let us eat and drink, for tomorrow we die!"
a. Otherwise, what will they do who are baptized for the dead, if the dead to not rise at all? What was being baptized for the dead? It is a mysterious passage, and there have been more than thirty different attempts to interpret it.
i. The plain meaning of the original language is that some people are being baptized on behalf of those who have died. Paul's point is "If there is no resurrection, why are they doing this? What is the point if there is no life after death?"
ii. Significantly, Paul does not say, "we baptize for the dead," but asks what will they do who are baptized for the dead, and Why then are they baptized for the dead? Therefore, Paul is referring to a pagan custom of vicarious baptism for the dead. "Paul simply mentions the superstitious custom without approving it and uses it to fortify his argument that there is a resurrection from the dead." (Mare)
iii. Paul certainly does not approve of the practice; he merely says that if there is no resurrection, why would the custom take place? The Mormon practice of baptism for the dead is neither Scriptural nor sensible.
iv. Paul's point is plain: "The pagans even believe in the resurrection because they baptize for the dead. The pagans have the sense to believe in resurrection, but some of you Corinthian Christians do not!"
v. Clarke said of this verse, "This is certainly the most difficult verse in the New Testament; for, notwithstanding the greatest and wisest of men have laboured to explain it, there are to this day nearly as many different interpretations of it as there are interpreters."
https://www.blueletterbible.org/Comm/guzik_david/StudyGuide_1Cr/1Cr_15.cfm?a=1077029