Irenaeus of Lyons, writing in the latter half of the 2nd century (within about 80-90 years after the death of the Apostle John) perhaps provides more information in his great work, "Against Heresies"
"A certain Cerenthius in Asia taught that the world was not made by the First God but by a certain Power far separated and distant from the Principality which is over all and ignoring the God of all. Jesus was not born of a virgin, for that is impossible, but was the son of Joseph and Mary by generation like all other men, and he was better than them in justice, prudence, and intelligence. After his baptism the Christ came down into him in the form of a dive from the Principality which is over all and then he proclaimed the unknown Father and worked miracles. At the end, the Christ flew away from Jesus, Jesus suffered and was raised, but the Christ remained impassible, being spiritual. (1.26.1)"
Notice the dichotomy between "Jesus" and "the Christ". That, along with the flesh-soul dualism, is quite specific and consistent with the heresy John condemns in 1st John 2:22:
Who is the liar but he who denies that Jesus is the Christ?The heresy itself is also eerily similar to the modern "Jesus of history v. Christ of Faith" dichotomy popularized by radical New Testament critics like Marcus Borg (who is, shocker, an Episcopalian) and John Crossan. The only difference is that unlike Cerenthius Borg and Crossan deny the bodily resurrection of Jesus, suggesting that Jesus' is still in his grave and the apostles merely experienced the "Christ of Faith" in a spiritual/metaphorical sense when they felt like sunshine and spring flowers the Sunday after Jesus was brutally executed. Cerenthius, heretic though he was, at least accepted the fact of the bodily Resurrection.
In any case, Irenaeus says more about Cerenthius and even passes down an account from Polycarp (a martyr and a follower of the Apostle John) linking Cerenthius to the Apostle John and the church in Ephesus:
"Some heard him [Polycarp] say that John the Lord's disciple was going to the bath in Ephesus when he saw Cerenthius inside and jumped out of the bath wihtout bathing, saying that he feared the bath would fall down since Cerenthius, the enemy of the truth, was inside...(3.3.4)"
This does not necessarily mean that Cerenthius was the false teacher denounced by John in 1st John but the similarities between his teachings and those John confronts are striking. I. Howard Marshal, in his commentary on 1st John, writes:
"Irenaeus attacked a heretic called Cerenthius who held that Christ descended upon Jesus at his baptism and departed again before he suffered and died. In the view of these heretics the heavenly Christ did not suffer and die nor did he shed his blood to be our Savior. Now it is true that there are other features of the teaching of Cerenthius which are not reflected in 1 John, so that we cannot simply identify the heretics with Cerenthius and his colleagues. Nevertheless, this aspect of the Cerenthian heresy still appears to give the closest parallel to that of John's opponents. (pp. 157-8, The First Epistle of John, I. Howard Marshal, Eerdmans NICNT 1978)
Always nice to have extra-biblical data to flesh out the context in which New Testament books and letters were written.