Do the apostle Paul’s words found at 1 Corinthians 15:29 mean that some Christians back then got baptized on behalf of dead people?
No, neither the Bible nor history indicates that such was done.
The way that this text reads in many Bibles has led some to think that water baptism on behalf of the dead was carried out in Paul’s day. For example: “Now if there is no resurrection, what will those do who are baptized for the dead?”—New International Version.
However, note the comments of two Bible scholars. Dr. Gregory Lockwood said that the idea that baptisms were performed “on behalf of persons who had already died” would be “a form of baptism, which as far as can be determined, was without historical or biblical parallel.” Similarly, Professor Gordon D. Fee wrote: “There is no historical or biblical precedent for such baptism. The N[ew] T[estament] is otherwise completely silent about it; there is no known practice in any of the other churches nor in any orthodox Christian community in the centuries that immediately follow.”
The Bible says that Jesus’ followers were to “make disciples of people of all the nations, baptizing them . . . , teaching them to observe all the things” he had commanded. (Matt. 28:19, 20) Before a person could become a baptized disciple, he needed to learn about, believe in, and obey Jehovah and His Son. Someone who was already dead and in the grave could not do that; nor could a living Christian do it for him.—Eccl. 9:5, 10; John 4:1; 1 Cor. 1:14-16.
What, then, was Paul saying?
Some Corinthians denied that the dead would be resurrected. (1 Cor. 15:12) Paul refuted that view. He pointed out that he ‘daily faced death.’ Of course, he was still alive. But despite experiencing dangers, he was confident that after death he would be resurrected as a powerful spirit, even as Jesus was.—1 Cor. 15:30-32, 42-44.
The Corinthians needed to realize that being anointed Christians meant that they would face daily trials and die before they could be resurrected. Being “baptized into Christ Jesus” involved being “baptized into his death.” (Rom. 6:3) Their figurative baptism resulted in a course that would lead to their literal death and resurrection to heaven.
More than two years after Jesus got baptized in water, he told two of his apostles: “With the baptism with which I am being baptized, you will be baptized.” (Mark 10:38, 39) Jesus was not then being baptized in water. He meant that his ongoing course of integrity would lead to his actual death. Paul wrote that anointed ones would “suffer together so that [they might] also be glorified together.” (Rom. 8:16, 17; 2 Cor. 4:17) So they too would have to die to be resurrected to life in heaven.
Accordingly, Paul’s statement can accurately be rendered: “Otherwise, what will they do who are being baptized for the purpose of being dead ones? If the dead are not to be raised up at all, why are they also being baptized for the purpose of being such?”