A.T. Robertson Commentary 1 Corinthians 15:29

"Else what shall they do that are baptized for the dead? If the dead are not raised at all, why then are they baptized for them?" — 1 Corinthians 15:29 (ASV)

Else (επε). Otherwise, if not true. On this use of επε with ellipsis see on 5:10; 7:14.

Which are baptized for the dead (ο βαπτιζομενο υπερ των νεκρων). This passage remains a puzzle. Stanley gives thirteen interpretations, no one of which may be correct. Over thirty have been suggested. The Greek expositors took it to be about the dead (υπερ in sense of περ as often as in 2 Corinthians 1:6) since baptism is a burial and a resurrection (Romans 6:2–6). Tertullian tells of some heretics who took it to mean baptized in the place of dead people (unsaved) in order to save them. Some take it to be baptism over the dead. Others take it to mean that Paul and others were in peril of death as shown by baptism (see verse 30).

At all (ολως). See on 5:1.