It is significant that among the first principles taught in the unfolding events of the Restoration, the principle of redeeming the dead was emphasized. Moroni, then a resurrected being, appeared to young Joseph Smith in 1823, and, among many things, taught the eventual return of Elijah "before the coming of the great and dreadful day of the Lord."
"And he shall plant in the hearts of the children the promises made to the fathers, and the hearts of the children shall turn to their fathers. If it were not so, the whole earth would be utterly wasted at his coming." (Joseph Smith—History 1:38-39.)
During the October 2000 general conference, Elder D. Todd Christofferson of the Presidency of the Seventy said, "Our work for the dead bears witness that Jesus Christ will come again to the earth."
Speaking of the aforementioned scripture, he continued: "In an inspired commentary on this scripture, the Prophet Joseph Smith stated, 'The earth will be smitten with a curse unless there is a welding link of some kind or other between the fathers and the children, upon some subject or other — and behold what is that subject? It is the baptism for the dead.' (See Doctrine and Covenants 128:18.)
"The vicarious ordinances we perform in temples, beginning with baptism, make possible an eternal welding link between generations that fulfills the purpose of the earth's creation. Without this, 'the whole earth would be utterly wasted at [Christ's] coming.' Elijah has, in fact, come as promised to confer the priesthood power that turns hearts and establishes the welding links between the fathers and the children so that once again what is bound on earth 'shall be bound in heaven.' When he came, Elijah declared, 'The keys of this dispensation are committed into your hands; and by this ye may know that the great and dreadful day of the Lord is near, even at the doors.'
"We are anxiously about the task of searching out our fathers and mothers of generations past and binding them to us and us to them. Is not this the strongest possible evidence of our conviction that Jesus Christ will come again to reign upon the earth? We know He will, and we know what He expects we will have done in preparation for His return."