Yes, the LDS church does baptisms for the dead with or without the permission of the person’s relatives or descendants. The LDS church has come under fire for baptizing millions of people, including holocaust victims, Anne Frank, Albert Einstein, and probably even Adolf Hitler. [An interesting note is that the LDS people believe they are the literal descendants of one or more of the lost tribes of Israel.]
The Biblical justification for this is based on this rather cryptic verse: 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?
As with most practices and beliefs in the LDS church, the baptism for the dead and the giving of the Eucharist to the dead was practiced in one or another location of the early orthodoxy of the Christian Church. This can be seen by decisions made in two late fourth century church councils. The fourth canon of the Synod of Hippo, held in 393, declares, “The Eucharist shall not be given to dead bodies, nor baptism conferred upon them.” Four years later, the sixth canon of the Third Council of Carthage reaffirmed the Synod banning the practices.
The LDS church would maintain that this was the result people meddling around with doctrine after the loss of and lack of replacement of the apostles and due to the lack of priesthood authority and is one of the “plain and precious things” lost from the true Gospel.
The word “apostle” means one who walked with Christ and, except for Paul, there were none considered Apostles after the original ones died because by definition, it made no sense. No one else had walked with Christ; therefore, there could be no more Apostles. In the LDS church, an Apostle is a “special witness of the name of Jesus Christ who is sent to teach the principles of salvation to others.”
“Gospel” is defined by orthodox Christianity as an account, often written, that describes the life of Jesus of Nazareth. According to the bible, the “Gospel”, is also defined as the “Word” that comes from God. To the LDS, it refers to the Laws and Ordinances of the church one must adhere to in order to obtain Exaltation.
I do not know if there is a consensus in the orthodoxy about what the verse Paul wrote is supposed to mean. This is typical of Paul’s writings.
The LDS position covers this situation:
Let’s say that without accepting Christ as your personal savior, one is damned to Hell for all eternity—a fairly common Christian teaching. Jesus is reported as saying “Go ye into all the world, and preach the Gospel to every creature. He that believeth, and is baptized, shall be saved; but he that believeth not shall be damned” (Mark 16:15-16). Many Christian churches state without reservation that no baptism means going to Hell. [This is one of the things some anti-Choice people assert, that aborting a “person” means they die without baptism and are going to Hell. This belief makes sane discussion all but impossible.]
So, then, the question asked of countless Sunday school teachers by kids who ask, “if God can do anything, can He make a rock too heavy for Him to loft?” What about all the people who died before Jesus came into the world? Is Moses going to Hell? Abraham? What about all those in deepest darkest Africa? How can God do that? It just is not fair. It’s fun to watch the teacher squirm with this one. I know. I was one of those who asked these types of questions.
The LDS answer is the vicarious baptism—and other Ordinances— for those who have died, and this is why they do genealogy, to find the names of those who have gone before. I do not know if it is doctrinal, but many LDS people believe they cannot go to the best part of heaven unless all their ancestors are also there.
So, the lists are made and then in the temple—which is not a house of worship, but where Ordinances are performed—people are baptized for those who have died.
The LDS believe that all will have a chance to accept the true Gospel after death and before the final judgement and that having so accepted, they will have had to have had the Ordinances performed for them literally, and this vicarious act satisfies this requirement. Makes as much sense as hundreds of other Old Testament practices we have abandoned.
Is the practice odd? Yes. Is it wrong? I don’t know. We each have to make up our own minds on this.