Family History Work and Genealogy
http://www.lds.org/study/topics/family-history-work-and-genealogy?lang=eng “In the spirit world, the restored gospel is preached to those who died without receiving it in mortality. Many of those in the spirit world accept the gospel, but without a body they cannot receive the ordinances necessary for salvation. The primary purpose of family history work is to obtain names and other genealogical information so that temple ordinances can be performed in behalf of deceased ancestors.
On April 3, 1836, the prophet Elijah came to Joseph Smith and Oliver Cowdery in the Kirtland Temple. He conferred upon them the sealing power of the priesthood, making it possible for families to be sealed throughout the generations. In conferring this power, he fulfilled the prophecy that the Lord would send him “to turn the hearts of the fathers to the children, and the children to the fathers” (see D&C 110:14-16; see also Malachi 4:5-6).”
Luke 16:30-31; “And he said, Nay, father Abraham: but if one went unto them from the dead, they will repent. 31 And he said unto him, If they hear not Moses and the prophets, neither will they be persuaded, though one rose from the dead.”
1 Timothy 1:4; “Neither give heed to fables and endless genealogies, which minister questions, rather than godly edifying which is in faith: so do.”
Malachi 4:5-6; “Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the LORD:6 And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.”
You really should read Luke 16:19-31 to understand the two verses I listed here from Jesus’ parable of Lazarus and the rich man.
The Malachi passage is about John the Baptist coming in the spirit of Elijah to declare it is time for the people to repent for the day of salvation is at hand! It was time for the people to turn their hearts to the Father.
From our passage in Luke it’s obvious no dead people are coming to earth to witness to anyone. Furthermore, the Bible is clear when God said everyone would know Him. People have not lived on this earth without a chance of knowing who He is. He’s made Himself known from one generation to the next. Romans 1:16-20, Jeremiah 31:34, 32:40, Ezekiel 36:26-27. Thinking that you need to be baptized for dead people is believing a lie that Satan has thrown out to the people to take your focus off from God.
And finally, doing all the genealogical work to find the dead people’s names is another way to keep people away from the word of God and having time in your day for proper worship and study. All these things to keep someone busy is Satan’s way of diverting attention.