. . . there
are good grounds on which to conclude that it is some form of vicarious
baptism. In other words, the Corinthians’ baptism for the dead was a practice
believed to make some difference to the fate of the dead, to effect or ensure
their transfer to salvation. This is, of course, somewhat different from the
notion of the dead having an opportunity to respond to the gospel—the kind of
idea that may be hinted at in 1 Pet 4.6—but it is relevant enough to cast
considerable doubt over the assertion that notions of post-death
conversion/initiation are entirely absent from the NT. Likewise, John 5.25–29
may well indicate belief in a proclamation of Christ in the realm of the dead.
(Travis B. Williams and David G. Horrell, 1 Peter, 2 vols. [ICC
Commentary; London: T&T Clark, 2023], 2:349])