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? 1 Cor. 15:29.
He asks, “What will they do who are baptized for the dead, if the dead do not rise?” . . . Do not then suppose that the apostle here indicates that some new god is the author and advocate of this practice. Rather, it was so that he could all the more firmly insist upon the resurrection of the body, in proportion as they who were baptized for the dead resorted to the practice from their belief of such a resurrection. We have the apostle in another passage defining “only one baptism.” Therefore, to be “baptized for the dead” means, in fact, to be baptized for the body. For, as we have shown, it is the body that becomes dead. What, then, will they do who are baptized for the body, if the body does not rise again? Tertullian (c. 207, W), 3.449, 450.
Inasmuch as “some are also baptized for the dead,” we will see whether there is a good reason for this. Now it is certain that they adopted this [practice] with a presumption that made them suppose that the vicarious baptism would be beneficial to the flesh of another in anticipation of the resurrection. For unless this is a bodily resurrection, there would be no pledge secured by this process of a bodily baptism. Tertullian (c. 210, W), 3.581, 582.