1 Corinthians 15:29 KJV
29Else 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?
After having discussed the order of the resurrection in the preceding verses, Paul immediately asked a question without directly giving the answer because it's a rhetorical question that the reader of the Bible is supposed to know the answer to. Often this verse is misinterpreted by LDS folk to mean that it's possible to perform a substitutionary water baptism for someone who has died, under the belief that water baptism is a prerequisite for eternal salvation; this part is false.
However, Paul asks these question in regards to the order of the resurrection of the righteous, not eternal salvation. Now I will give you the correct answers to Paul's rhetorical questions in plain English showing a few different Bible versions with it.
Question 1:
Else what shall they do which are baptized for the dead, if the dead rise not at all?
KJV
Now if there is no resurrection, what will those do who are baptized for the dead?
NIV
Otherwise, what do people mean by being baptized on behalf of the dead?
ESV
Answer 1:
We can reverse engineer Paul's line of thinking here by questioning why they are getting immersed if there is no resurrection of the dead. There is a resurrection of the dead and in order to take part in the resurrection you must be water baptized. That's basically what Paul is suggesting here and I will provide numerous scriptures that support it later in this post.
Question 2:
why are they then baptized for the dead?
KJV
If the dead are not raised at all, why are people baptized for them?
NIV
If the dead are not raised at all, why are people baptized on their behalf?
ESV
Answer 2:
This question is similar to the first question and so is the answer. The answer is that people are attempting to help deceased people by performing a water baptism for them so that they can be resurrected. There is no evidence from scripture that a substitutionary posthumous water baptism is effective to qualify a dead person for a resurrection, but there is evidence that a water baptism can provide a living person a resurrection.
After we understand these vital clues about Paul's water baptism theology, we can more accurately understand what the purpose of water baptism is he preached everywhere he went. It isn't about eternal salvation of the soul as some people think;
Paul meant that water baptism is literally about becoming eligible to have an immortal resurrected body.
Paul is teaching that water baptism is literally necessary to have a resurrected body:
Romans 6:4-5 KJV
4Therefore we are buried with him by baptism into death: that like
as Christ was raised up from the dead by the glory of the Father, even so
we also should walk in newness of life.
5For if we have been
united with Him like this in His death,
we will certainly also be united with Him in His resurrection.
Again:
Colossians 2:12
12Buried with him in baptism, wherein also ye are
risen with him through the faith of the operation of God, who hath
raised him from the dead.
Again:
Galatians 3:27 KJV
27For as many of you as have been baptized into Christ have put on Christ.
Once you understand that water baptism is about the righteous getting a resurrected body in the first resurrection, you'll understand why Paul often made water baptism less important than preaching the gospel. It is more important to save as many souls as possible with the Gospel of Christ than it is to get people into the first resurrection:
1 Corinthians 1:14-17 KJV
14I thank God that I baptized none of you, but Crispus and Gaius;
15Lest any should say that I had baptized in mine own name.
16And I baptized also the household of Stephanas: besides, I know not whether I baptized any other.
17For Christ sent me not to baptize, but to preach the gospel: not with wisdom of words, lest the cross of Christ should be made of none effect.
