Why do we go into the temples to be sealed, husbands and wives, and children to parents, and why are we commanded to have this work done, not only for ourselves, but also to be sealed to our fathers and mothers, and their fathers and mothers before them, back as far as we can go? Because we want to belong to that great family of God which is in heaven, and, so far as the Church is concerned, on earth. That is why. Eventually, when this work is perfected, and Christ delivers up to his Father the keys and makes his report, and death is destroyed, then that great family from the days of Adam down, of all the righteous, those who have kept the commandments of God, will find that they are one family, the family of God, entitled to all the blessings that pertain to the exaltation.

Elder Joseph Fielding Smith