1 Corinthians 15:29 - Coke's Commentary on the Holy Bible

Else what shall they do, &c.— "Such are our views and hopes, as Christians; else, if it were not so, what should they do who are baptized in token of their embracing the Christian faith in the room of the dead, who are just fallen in the cause of Christ, but whose places are filled up by a succession of new converts, who immediately offer themselves to succeed them, as ranks of soldiers that advance to the combat in the room of their companions,who have just been slain in their fight. If the doctrine that I oppose be true, and the dead are not raised at all, why are they, nevertheless, thus baptized in the room of the dead, as cheerfully ready, at the peril of their lives, to keep up the cause of Jesus in the world?" It would be almost endless to enumerate, and much more to canvass, all the interpretations which have been given of this obscure phrase, υπερ των νεκρων. There is no reason to believe that the superstitious custom, mentioned by Epiphanius, of baptizing a living person, as representing one who had died unbaptized, is here referred to; it is more likely to have arisen from a mistake of this passage than to have been so early prevalent. Mr. Cradock's supposing it to allude to washing dead bodies, neither suits the grammar, nor really makes any significant sense. The primitive Christians were accustomed, in general, to reserve the baptizing of adults for solemn occasions, particularly for Whitsunday. But it is not at all improbable, that when any eminent Christians died, especially martyrs, some were chosen out of the catechumens who were preparing for baptism, and, in honour of these eminent saints, and to fill up their places, were baptized for the dead. Dr. Whitby, by the words, for the dead, understands, "for that Jesus, who, according to their doctrine, must still be dead;" and he observes, that the plural οι νεκροι is frequently used in scripture, when one person is spoken of; and that the resurrection νεκρων — of the dead in general, is thrice mentioned by this Apostle, when speaking of the resurrection of Christ alone. See the Reflections.