Hello @stone,
First of all, a warm welcome to you and thank you for your question. Glad you’ve taken the time to engage with the UP community. Just so you’re aware, where we’re coming from, we hold to the historic Christian view that salvation comes through grace and through a personal faith in Jesus Christ. Please check out our statement of faith to learn more.
While there are differences between our beliefs and LDS beliefs, happy to respond to a sincere question.
Now, to your question about baptism on behalf of the dead. This practice is mentioned in 1 Corinthians 15:29, but it’s important to note that Paul refers to it in passing and does not endorse it.
1 Corinthians 15:29 ESV - 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?
CSB study bible states, “Being baptized for the dead probably refers to the practice, apparently unique to the Corinthian church, of someone undergoing baptism on behalf of a believer who had died without undergoing baptism. Paul was not condoning this practice, and certainly Scripture no where directs us to conduct such baptisms. Paul simply pointed out that it was meaningless for the Corinthians to enact such practices if they disbelieved in the resurrection of the dead”.
So rather than advocating for the practice, Paul is using it to reinforce belief in the resurrection. He refers to what “others” are doing, not what God commanded.
The broader teaching of the Bible makes it clear that each person has one life and one opportunity to respond to God:
Hebrews 9:27-28 NLT - And just as each person is destined to die once and after that comes judgment, so also Christ was offered once for all time as a sacrifice to take away the sins of many people. He will come again, not to deal with our sins, but to bring salvation to all who are eagerly waiting for him.
This verse teaches that there is no second chance after death. No rite can be performed to have a second opportunity after death to receive salvation.
Baptism for the dead is performed on behalf of others, but the Bible is clear that each person is accountable for their own choices.
Romans 14:12 ESV - So then each of us will give an account of himself to God.
Salvation is personal, and baptism is an outward expression of faith made by a living believer, in response to their own decision to follow Christ.
Hope this helps. Again, thank you for your question. God bless!