Themes on 'Redemption of the Dead' is not only depicted in historical Christian art but it is also found in ancient Christian writings. 'Baptism for the Dead' is just one aspect of this concept of redeeming the dead that was taught by the Early Christian Church.
"Forgotten Books of Eden"
In the "Forgotten Books of Eden," Adam and Eve are given the covenant and a promise that Christ will come and raise them from hell. How they are given the covenant and how they are "raised" up to life in the Garden, and how they are "raised up" or "harrowed" or "resurrected" from their graves (the pit, underworld, hades, limbo, purgatory, etc.), is interesting:
"And if thou saidst, 'Give me of the Water of Life that I may drink and live'-- it cannot be this day, but on the day that I shall descend into hell, and break the gates of brass, and bruise in pieces the kingdom of iron. Then will I in mercy save thy soul and the souls of the righteous, to give them rest in My garden. And that shall be when the end of the world is come." The next two verses is derived from old Christian lore that Adam's grave was traditionally believed to be under Christ's cross, hence the "water of life" that the pre-incarnate Christ offers Adam and Eve, is a type of baptism that their remains will be given, when Christ's blood flows down onto their remains: "For My blood shall be the Water of Life unto thee, at that time, and not to thee alone, but unto all those of thy seed who shall believe in Me; that it be unto them for rest for ever." (See: The Lost Books of The Bible and the Forgotten Books of Eden, (USA, Newfoundland: World Bible Publishers, Inc., 1926 and 1927), The First Book of Adam and Eve, pp. 5-28, see Book One, chapters 3-15 and chapter xlii, verses 5-8, p. 28).
"But unto every one of us is given grace according to the measure of the gift of Christ.
Wherefore he saith, When he ascended up on high, he led captivity captive, and gave gifts unto men. (Now that he ascended, what is it but that he also descended first into the lower parts of the earth? He that descended is the same also that ascended up far above all heavens, that he might fill all things.)" (Ephesians 4:7-10)