Q. 1. In the First Letter to the Corinthians, there is a reference to the baptism of the dead.
"Otherwise, what will those people do who receive baptism on behalf of the dead? If the dead are not raised at all, why are people baptized on their behalf?" [1 Cor. 15:29]
What does the Catholic Church have to say about this matter?
A. 1. First of all, as taught by the Catholic Church, you can never take one line in the Bible and give it an interpretation. You have to take the entire Chapter and read the line in context of the subject being covered.
The issue at hand that St. Paul was addressing was instances where catechumen died before they could receive the Sacrament of Baptism. Since they had been under instructions but not yet baptized, a member of the faith community received the Sacrament of Baptism in their name. The Catholic Church condemned this practice as it did not involved the administration of a Sacrament. The Sacraments are for the living.
At the same time, some of the Christians were starting to doubt in the resurrection. The reason that St. Paul brought up the subject of the baptism of the dead is because he was questioning the Corinthians, "How could they believe in the resurrection by baptising the dead and yet not believe in the resurrection at the same time by doubting in it?" Paul was pointing out that their thinking was contradictory.