In his Panarion, book 1 section 28 (Against the Cerinthians), Epiphanius of Salamis, around AD 377, wrote the following which is a witness that some within the broad Christian spectrum were engaged in baptism for the dead:
6:1 In turn this Cerinthus, fool and teacher of fools that he is, ventures to maintain that Christ has suffered and been crucified but has not risen yet, but he will rise when the general resurrection of the dead comes.
6:2 Now this position of theirs is untenable, both the words and the ideas. And so, in astonishment at those who did not believe in the coming resurrection of the dead, the apostle said, 'If the dead rise not, then is Christ not raised;' 'Let us eat and drink, for tomorrow we die' and, 'Be not deceived; evil communications corrupt good manners.'
6:3 Again, he likewise gives their refutation to those who say that Christ is not risen yet by saying, 'If Christ be not raised, our preaching is vain and our faith is vain. And we also are found false witnesses against God, because we testified against God that he raised up Christ, if so be that he raised him not up.' For in Corinth too certain persons arose to say there is no resurrection of the dead, as though it was apostolic preaching that Christ was not risen yet and the dead are not raised (at all).
6:4 For their school reached its height in this country, I mean Asia, and in Galatia as well. And in these countries I also heard of a tradition which said that when some of their people died too soon, without baptism, others would be baptized for them in their names, so that they would not be punished for rising unbaptized at the resurrection and become the subjects of the authority that made the world.
6:5 And the tradition I heard of says that this is why the same holy apostle said, 'If the dead rise not at all, why are they baptized for them?' But others explain the text satisfactorily by saying that, as long as they are catechumens, the dying are allowed baptism before they die because of this hope, showing that the person who has died will also rise, and therefore needs the forgiveness of his sins through baptism.
6:6 Some of these people have preached that Christ is not risen yet, but will rise together with everyone; others, that the dead will not rise at all.
6:7 Hence the apostle has come forward and given the refutation of both these groups and the rest of the sects at once on the subject of resurrection. And in the testimonies that he gave in full he produced the sure proof of the resurrection, salvation and hope of the dead
6:8 by saying, 'This corruptible must put on incorruption, and this mortal must put on immortality,' and again, 'Christ is risen, the first fruits of them that slept.' This was to refute both kinds of sects at once and truly impart the unsullied doctrine of his teaching to anyone who wanted to know God's truth and saving doctrine.
I mentioned this reference to baptism for the dead as it refutes Mike Thomas who wrote the following in an article "The Mormon God":
The concept is not mentioned elsewhere in the Bible or in other early Christian documents, with two exceptions. If it had been as important or as frequent a part of the original Gospel as it is to one of our latter-day denominations, we would expect to find many references to it in writings by Christians who lived a short time after Jesus. Yet, barring one reference by Clement of Alexandria in Excerpt 22 of Excerpta ex Theodoto and one by Tertullian in Against Marcion 5.10, 1 Corinthians 15.29 stands alone in the age of Saint Paul and for centuries afterwards.
For further refutations of Mike Thomas on this and other issues, see:
