Some scholars are too cautious to link 1 Peter 3:19 on Christ preaching in the spirit prison with 1 Peter 4:6 on the general preaching to the dead. But the key words for preaching in those verses are kerusso and euangelizo, the only two words in the New Testament that are consistently used of the missionary proclamation of the gospel. These synonyms show that Peter is talking of similar events. God cannot reach all his children without sending messengers to the worlds of the living and of the dead. And the two Greek words just mentioned constantly refer to teaching baptism as well as faith. For instance, nearly every baptism mentioned in Acts is preceded by one of these words, generally translated "preach" or "preach the gospel." Christ's commission to the Twelve at the end of Matthew and Mark commands baptism as the immediate result of the preaching. Thus, Peter virtually suggests Paul's baptism for the dead in his verbs for preaching to the dead, the same verbs that are found in the above early Christian references on Christ's visit to the spirit world. In turn, Paul virtually suggests Peter's concern for the living and the dead in the context of baptism for the dead in 1 Corinthians 15:29, as already discussed in the chapter treating that letter. And the two interrelated doctrines come together in the document known as the Shepherd of Hermas, which derives its name from a series of visions and teachings from an angel as a shepherd. In the second century the Muratorian Canon gives the date as midcentury: "But Hermas composed the Shepherd quite recently in our times in the city of Rome, while his brother, Pius, the bishop, occupied the chair of the city of Rome."
The Shepherd of Hermas is not a source for new doctrine, for its main theme is preserving the faith. Its author is dutiful and conservative, seeking to hold to what he had been taught in a Christian career going back to the turn of the century and Clement of Rome, whom he mentions.... Thus, he is a source for the common doctrines and practices of the Christian Church. And he welds preaching to the dead to baptism for the dead. These doctrines come in the allegory of building the tower, which the angel defines as the Church [Anderson cites The Shepherd of Hermas, Similitude 9.16.2-4 (Loeb Classical Library, Kirsopp Lake trans.) I have a slightly different translation with essentially the same content: The Third Book of Hermas, Similitude 9, in The Lost Books of the Bible, Alpha House, Inc., Newfoundland, 1926, reprinted by World Publishing, New York, 1972, pp. 247-267; see especially verses 150-159, p. 258. Another translation is available online at
http://www.newadvent.org/fathers/0201309.htm.] The three lower courses of stones represent the foundation generations of the righteous men of the Old Testament, with the last and largest number of 40 representing the "prophets and teachers of the preaching of the Son of God." These have the seal, clearly defined as baptism by (1) the requirement "to come up through the water that they might be made alive"; (2) the quotation of John 3:5, referring to water as the way to "enter into the kingdom of God"; and (3) the summary, "the seal, then, is the water." As the following passage begins, Hermas's messenger is explaining that the pre-Christian dead - "who had fallen asleep" - were also baptized; this is followed by the explanation that the New Testament priesthood bearers had been baptized again to make this possible [Anderson cites Sim. 9.16.3-7; see also The Third Book of Hermas, Sim. 9, vs. 152-160]:
"So these also who had fallen asleep received the seal of the Son of God and 'entered into the kingdom of God'. . . . This seal, then, was preached to them also, and they made use of it 'to enter into the kingdom of God.'"
"Why, Sir," said I, "did the 40 stones also come up with them from the deep, although they had received the seal already?"
"Because," said he, "these apostles and teachers who preached the name of the Son of God, having fallen asleep in the power and faith of the Son of God, preached also to those who had fallen asleep before them, and themselves gave to them the seal of the preaching. They went down therefore with them into the water and came up again, but the latter went down alive and came up alive, while the former, who had fallen asleep before, went down dead but came up alive. Through them, therefore, they were made alive, and received the knowledge of the name of the Son of God. . . . For they had fallen asleep in righteousness and in great purity, only they had not received this seal. You have then the explanation of these things also."
Some parts of the above message are obvious, and others are clear in the light of Hermas's purpose in writing. Since the above words explain the vision-parable or allegory, they relate to Christian doctrine and practice. The plainest point is that after death the "apostles and teachers" continued their missionary labors in the spirit world, adding the dimension that preaching to the dead continued after Christ. The consequences of that doctrine are revolutionary. Thus, the spirits do not merely receive an announcement of Christ's victory; continued preaching assumes individual growth there and acceptance of gospel principles beyond simple belief. Thus, the emphasis on baptism for the pre-Christian righteous logically fits the scheme. But what kind of baptism? . . .
Hermas's book proves that he is a Christian traditionalist, and the spirit-world passage underlines the point by three repetitions of the words of John 3:5 on entering the kingdom of God through water. He is so bound by scripture that he cannot imagine salvation without baptism, and he obviously writes with consciousness of Peter's words on preaching in the spirit world. Thus, Hermas also writes with awareness of Paul's reference to baptisms of the living for the dead. Those "fallen asleep" in his passage are, of course, the dead, and his subject closes with plain words about the righteous who had died without baptism. So Hermas is discussing what Christians believe about baptism for the dead; so this "pious and conscientious" author certainly refers to the known baptism for the dead and not the unknown. That explains his question to the angel, for he found it contradictory that the New Testament priesthood leaders went into the deep again, the symbol of their personal baptisms. If they would merely baptize others, there could be no puzzle. So Hermas's question was really about rebaptism of those already baptized. The explanation was that both groups go into the water, but the effect of remission of sins is only for those dying without baptism. This cooperative baptism is proxy baptism, the only type mentioned by the "apostles and teachers" that he refers to. The joint immersion in water is part of the symbolism not expressly interpreted, referring to the earthly baptisms that were a shared experience of the living and the dead.