The practice of being baptized for those who have died is based upon a wrong understanding of I Corinthians 15:29. The New Testament Church did not follow this practice, and the apostle Paul did not teach it. This custom was introduced into the professing Christian world about AD 150 by Marcion, a man who created his own religion and established his own church in Rome in AD 144.
The Bible clearly shows that, before a person may be baptized, he must first repent (Acts 2:38) and believe (Mark 16:16; Acts 16:31, 33). The dead are not able to repent or believe, because "the dead know nothing" (Ecclesiastes 9:5). Baptism is for the living; it is a symbol whereby the living acknowledge their sins, figuratively die with Christ in a watery grave, and rise out of that watery grave to live a new, righteous life through Jesus Christ and the indwelling of the Holy Spirit (Romans 6:4; 8:9; Galatians 2:20).
Baptism is also a symbol of the resurrection. To rise up out of the watery grave is to acknowledge belief in the resurrection of the dead (Romans 6:1-5). To surrender one's life to Christ now, to crucify the self now, to be baptized—all this is foolish unless there is a resurrection of the dead. If there were no hope of the resurrection, life could be summed up this way: "Let us eat and drink; for tomorrow we die" (I Corinthians 15:32).
I Corinthians 15:29 now becomes clear. The whole of I Corinthians 15 concerns the resurrection from the dead. Paul cites the example of those who were baptized as a proof of the resurrection. Their actions symbolized their hope that they would live again. The resurrection is the hope of the dead.
Paul's question seems to be, "Why are they baptized for the dead, if the dead do not rise at all?" (New King James Version). However, this verse is not correctly translated from the Greek. Paul is not talking about being baptized "in the place of," "on behalf of," or "for" the dead. The Greek word translated "for" is huper, and it has several meanings: "above," "over," "instead of," "for the realization of," or "for the hope of," depending upon the context.
For example, Paul declares, "For it is God who works in you both to will and to do for His good pleasure" (Philippians 2:13). As in I Corinthians 15:29, the Greek word translated "for" is huper. In Philippians 2:13, huper cannot mean "instead of." It would be senseless to say, "For it is God who works in you both to will and to do instead of His good pleasure"! Correctly translated, it means, "God works in you both to will and to do for the realization of His good pleasure" (The Analytical Greek Lexicon). What is God's "good pleasure"? "It is your Father's good pleasure to give you the kingdom," says Jesus (Luke 12:32). God works in us "in the hope of" giving us His Kingdom!
Thus, according to the context, hyper in I Corinthians 15:29 should be translated "for the hope of." Notice the verse again: "Otherwise, what will they do who are baptized for the hope of the dead, if the dead do not rise at all? Why then are they then baptized for the hope of the dead?"
What is the hope of the dead? The resurrection! Baptism illustrates the hope of the resurrection. One who is baptized rises out of a watery grave, symbolic of the resurrection. Paul is thus saying, "What good is it to be baptized if we do not rise in a resurrection from the dead? Why then should one be baptized for a hope that would never come true?" However, Paul affirms that, because Christ died and rose again, we have this true hope, the resurrection, to look forward to (I Corinthians 15:17-22).
This verse, then, has nothing to do with the false doctrine of baptism on behalf of the unbaptized dead.