To an outsider, the though of baptisms for the dead might seem a little strange. However, it is not. It was obviously a practice in the New Testament church, since Paul referenced the practice in 1 Corinthians 15:29. Some criticize the practice by saying that someone can’t perform a vicarious act (something for someone else) to save them. However, the very core of the gospel is a vicarious act: Our Savior Jesus Christ did something for us that we couldn’t do for ourselves—He died and resurrected, suffered for our sins, and will cleanse the repentant and make them fit for heaven.
The doctrine for baptisms for the dead is explained very well here by President Joseph Fielding Smith:
