I friend recently asked me about 1 Cor 15:29. I thought what I shared with him might be helpful to others…so here it is:
1 Cor 15:29 is a hard verse to understand. The translation is probably: "Otherwise, what will those do who are baptized for the dead?" [NET Bible (Biblical Studies Press, 2006]. The meaning, in paraphrase, is: "Otherwise what do those people think they are doing who have themselves baptized for the sake of the dead? If the dead are really not raised, what is the point of being baptized for them?" [Anthony C. Thiselton, The First Epistle to the Corinthians : A Commentary on the Greek Text (Grand Rapids, Mich.: W.B. Eerdmans, 2000), 1222.] I have read that there are as many as 200 interpretations of this verse. In reality, I think there are two that are feasible.
1) Some of the Corinthians were getting baptized in the place of believers who had died before they had been able to be baptized. They were doing it vicariously since those who had died had not had the opportunity to be baptized. Paul is not condoning the practice; he is just saying, "Why are you doing that if you say there is no resurrection? You obviously believe that there is life after death if you are concerned about what will happen to those who died, and did not have a chance to be baptized."
2) "For the dead" could mean "for the sake of the dead." It could mean that people came to Christ and were baptized because they wanted to be with their loved ones who had died and gone on before them.
The first interpretation is taken by this footnote in the NET Bible: ‘Many suggestions have been offered for the puzzling expression baptized for the dead. There are up to 200 different explanations for the passage; a summary is given by K. C. Thompson, ”I Corinthians 15, 29 and Baptism for the Dead,” Studia Evangelica 2.1 (TU 87), 647–59. The most likely interpretation is that some Corinthians had undergone baptism to bear witness to the faith of fellow believers who had died without experiencing that rite themselves. Paul’s reference to the practice here is neither a recommendation nor a condemnation. He simply uses it as evidence from the lives of the Corinthians themselves to bolster his larger argument, begun in 15:12, that resurrection from the dead is a present reality in Christ and a future reality for them. Whatever they may have proclaimed, the Corinthians’ actions demonstrated that they had hope for a bodily resurrection.’ [NET Bible (Biblical Studies Press, 2006].
The second interpretation is taken by Anthony Thiselton in his commentary. The following long quote is what he says:
‘In 1955 Maria Raeder (following G. G. Findlay) explicated more clearly than before a view which had been hinted at in earlier theories, namely that baptism for the sake of (ὑπέρ) the dead refers to the decision of a person or persons to ask for, and to receive, baptism as a result of the desire to be united with their believing relatives who have died. This presupposes that they would share the radiant confidence that they would meet again in and through Christ at the resurrection of the dead….If we consider such a scenario as that of a godly parent who longs for a son or daughter to come to faith, the nuance of ὑπέρ as for the sake of (in pragmatic terms) makes sense….
J. K. Howard fully supports and develops this view against those which favor vicarious baptism. He writes that baptism for (for the sake of) the dead is “not in order to remedy some deficiency on the part of the dead, but in order to be reunited with them at the resurrection.” Schackenburg agrees that “the argument does not step outside the frame of primitive Christian views and above all fits excellently into the resurrection chapter.” … Findlay…observes, “Paul is referring rather to a much commoner, indeed a normal experience, that the death of Christians leads to the conversion of survivors, who in the first instance ‘for the sake of the dead’ (their beloved dead) and in the hope of re-union, turn to Christ — e.g., when a dying mother wins her son by the appeal ‘Meet me in heaven!’ Such appeals, and their frequent salutary effect, give strong and touching evidence of faith in the resurrection” (Findlay’s italics). [Anthony C. Thiselton, The First Epistle to the Corinthians : A Commentary on the Greek Text (Grand Rapids, Mich.: W.B. Eerdmans, 2000), 1248-49.]