Paul uses this question to teach the Corinthians. It can be stated in active form. Alternate translation: "Otherwise it would be useless for Christians to receive baptism for the dead." (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-activepassive]])
Paul uses a hypothetical situation to argue that the dead are raised. To say that the dead are not raised is to say that people should not be baptized for the dead. But some people, probably some members of the church in Corinth, are baptized for the dead, so he infers those people are baptized for the dead because they believe that the dead are raised. (See: [[rc://en/ta/man/translate/figs-hypo]])
Paul uses this question to teach the Corinthians. It can be stated in active form. Alternate translation: "there would be no reason for them to have people baptize them on behalf of dead people." (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-activepassive]])