When we come across a passage within the Bible that is difficult to interpret or seemingly means something that contradicts another plain teaching of scripture, we must look at it through our understanding of the plain teaching of scriptures. Many choose to interpret the difficult passage first and then take perfectly plain scriptures and twist them to fit their interpretation of the difficult passage. Such we must not do, for such is handling the word of God incorrectly. We read in 2 Peter 3:16 the words of Peter who describes some of Paul’s epistles. He says, “As also in all his epistles, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures, unto their own destruction.” We must make sure that we do not wrest the scriptures to our own destruction.
So with those things in mind, we come to 1 Corinthians 15:29. “Else what shall they do which are baptized for the dead, if the dead rise not at all? Why are they then baptized for the dead?” The context of this particular passage is that of Paul’s proving to the Corinthians that the resurrection is going to happen. There were some in that day who were teaching that there was no resurrection (1 Corinthians 15:12). The Sadducees believed this too (Matthew 22:23). Some were teaching that the resurrection had passed (2 Tim. 2:18). Paul, however, was teaching that the resurrection was still coming and he used every available means to prove this to those in Corinth. So whatever this phrase means–that is, whatever the phrase “baptism for the dead” means–its significance is that the resurrection is still coming.
This phrase does not mean what those of the Mormon faith believe that it means. Mormons believe that one may be baptized for someone who is dead who was not a Mormon, and that person will then have the opportunity, after death, to accept the gospel. The long and short of this teaching is that you get a second chance to be saved after you die. This doctrine just does not mesh with other clear teaching that is within the scriptures. We read in Hebrews 9:27, “And as it is appointed unto men once to die, but after this the judgment.” In Luke 16:24 we read, that the rich man wanted Lazarus to come cool his tongue. Abraham replied, “And beside all this, between us and you there is a great gulf fixed: so that they which would pass from hence to you cannot; neither can they pass to us, that would come from thence” (Luke 16:26). The rich man knew that there was no escape because he then asked that Abraham send someone so that his brothers would escape this place. Jesus said in John 9:4 “I must work the works of him that sent me, while it is day: the night cometh, when no man can work.” The night when no man can work is after death. There are no more works that a person can do to affect one’s salvation after death. Perhaps a statement made by Isaiah makes this quite plain. He says, “Behold, for peace I had great bitterness: but thou hast in love to my soul delivered it from the pit of corruption: for thou hast cast all my sins behind thy back. For the grave cannot praise thee, death can not celebrate thee: they that go down into the pit cannot hope for thy truth. The living, the living, he shall praise thee, as I do this day: the father to the children shall make known thy truth” (Isaiah 38:17-19). Isaiah makes it clear that the time for forgiveness of sins is now. The time to be delivered from the pit of corruption is while one is living. Once one has died and is lost, there is no more hope for truth. The living are the ones who have the obligation to make known God’s truth. Paul says, “For he saith, I have heard thee in a time accepted, and in the day of salvation have I succored thee: behold, now is the accepted time; behold, now is the day of salvation” (2 Corinthians 6:2). Today is the day of the living. Today is the day of salvation.
So what does the phrase “baptism for the dead” mean? To be honest, I am not sure that I know what it means. There have been many different suggestions. Some have suggested that it refers to Christian baptism. These suggest that the phrase “the dead” refers to those who have died to sin and are being made alive in Christ. When they do this, they affirm the resurrection of Christ according to Romans 6:1-11. In this understanding, “the dead” is actually short hand for “the resurrection of the dead.” So that it would be baptism for the resurrection of the dead, i.e. in order to obtain the resurrection of the dead.
Others have suggested that Paul is referring to this group of people who are teaching that there is no resurrection for the dead implying some kind of self-contradiction among their own teaching. In other words, they were teaching that there was no resurrection, but they were practicing “baptism for the dead,” i.e. a vicarious baptism for those who had already died without being baptized. This, however, implied a resurrection because baptism is the form of the death, burial and resurrection of Christ. Those who hold this view say that Paul is not giving an endorsement to the doctrine, but merely stating that if one believed it, then it would imply that their doctrine of no resurrection is false.
Yet another interpretation states that those who had come to accept Christian baptism did so due to the influence of the faithful dead over the many years prior to their baptism. In this sense, they are being baptized for, that is, on account of, the dead who came before them. So if they were being baptized on account of the dead, then they should recognize that they would one day be raised. Finally, one view says that we have the punctuation wrong in the translation. Instead of reading as we would normally read, this view opts for the reading, “Else what shall they do that are baptized? If the dead are not raised at all, (baptism) is for the dead (spiritually). Why are they then baptized for the dead?” This view sees the phrase “the dead” as referring to people who are spiritually dead and thus baptism has no effect for them. I.E. if there is no resurrection, then baptism doesn’t take us out of death and into life, it just leaves us in a state of spiritual death and does nothing for us. We are merely being baptized to become dead. I don’t believe that I can say for certain that I know what this phrase means. I do know, however, that it does not endorse some type of proxy baptism for those who have died un-repented.
Source: http://gewatkins.net/please-explain-1-corinthians-1529-what-does-the-reference-to-baptism-of-the-dead-mean/
