It is always dangerous to interpret Scripture based on an isolated verse. Scripture needs to be looked at in both its immediate and complete context to understand it correctly.
What is baptism for the dead in 1 Corinthians 15:29?
Paul writes in 1 Corinthians 15:29: "Otherwise, what do people mean by being baptized on behalf of the dead? If the dead are not raised at all, why are people baptized on their behalf?" In reading the entire chapter, we see that Paul writes centrally about the surety of the resurrection and about Christ's power.
The Bible is clear that each individual must declare his or her faith in Jesus Christ to be saved. We cannot do this for each other or for a loved one, whether living or dead. Baptism is an important step of obedience in Jesus Christ, but not essential for salvation (Ephesians 2:8; Romans 3:28; 4:3; 6:3–4). Baptism for the dead, which some practice based on this verse (notably Mormons), is not biblical. Support for such a practice cannot be found in the Bible.
Throughout the centuries, many have tried to interpret the meaning of 1 Corinthians 15:29. Some conclude that Paul was making clear that there is a resurrection or that he is referring to a pagan custom those in Corinth were practicing. In any case, Paul does not condone it. What is clear is what "baptism for the dead" is not: an opportunity to be baptized in the place of someone else.
What is Christian baptism?
What does water baptism symbolize?
Is there a correct mode of baptism?
If a person desires baptism but cannot be immersed in water due to illness, disability, advanced age, etc., what should be done?
What do Mormons believe? What is Mormonism?
Truth about False Beliefs