1 Corinthians 15:29

Baptized for the dead] a very obscure allusion. There was somewhat later a practice, among certain sects of vicarious baptism; when a man died unbaptised, a friend would receive baptism in his stead. This may have already existed and be meant here. St. Paul mentions 'baptism for the dead,' without expressing his approval; but some think the practice sprang up later from a perversion of this passage. Two other views seem possible. (1) That of St. Chrysostom: 'Before baptism we confess our faith in “the resurrection of the dead,” and are baptised in hope of this resurrection.' (2) That of Godet, who regards the baptism as the baptism of suffering, the baptism with which those were baptised who have by martyrdom entered the Church invisible. But it can scarcely be denied that, as Dr. Dods says, 'the plain meaning of the words seems to point to a vicarious baptism, in which a living friend received baptism for a person who had died without baptism.'