[skinkinthegrass]

that's very strange, talk about "padding" your numbers!
why do they (lds) do this?...all the way back to pre-history.

[Allon]

The reason Mormons baptize in behalf of the dead is summarized pretty well in this Washington Post OP Ed, including the biblical references to why it's done. It's written by by Michael Otterson, the main LDS Church spokesman, so it's pretty close to an official answer. Hope that answers your question.

http://www.washingtonpost.com/blogs/guest-voices/post/what-baptism-for-the-dead-means-to-mormons/2012/02/23/gIQA2sIaVR_blog.html