Gnosticism is very much alive and they were the true Christians, the psychic Christians who are ignorant of the truth have always tried to suppress the Gnostic religion, in other words the pneumatic Christians who assert that Paul was actually a Gnostic and derive their Christology, Sacramentology and eschatology from the same Bible as read by millions of Christians worldwide.
I still think that Valentinian Christians will be a biggest threat to the Catholic religion.
“By attempting to bridge this gap, however, Valentinus and his followers became the proverbial wolves in sheep’s clothing. “The apparent similarity with orthodox teaching only made this heresy more dangerous – like poison disguised as milk.” Valentinian Gnosticism was “the most influential and sophisticated form of Gnostic teaching, and by far the most threatening to the church.”
What is their Christology?
“In Christ dwells all the pleroma of deity in bodily form.” Col 2:9
According to the Gnostics pleroma doesn’t just mean fullness as the psychic Christians interpret it instead pleroma has a local existence and actually forms the body of Christ. i.e. All other Aeons reside in Christ and form his mystical body. This is the esoteric message of St. Paul.
“Christ has each within him, whether human being or angel or mystery.” - (Gospel of Philip 56:14-15)
“People cannot see anything in the real realm unless they become it…if you have seen the spirit, you have become the spirit; if you have seen Christ, you have become Christ; if you have seen the Father, you will become the Father.” - (Gospel of Philip 61:20-32 cf. 67:26-27)
“It was quite amazing that Aeons were in the Father without being acquainted with him and that they alone were able to emanate, inasmuch as they were not able to perceive and recognize the one in whom they were” - (Gospel of Truth 22:27-32)
“All the emanations from the Father, therefore, are Pleromas, and all his emanations have their roots in the one who caused them all to grow from himself.” - (Gospel of Truth)
What is their Eschatology?
Its known as realized eschatology, i.e. you don’t have to wait for the second coming instead you can embrace your angel here and now and be one with him.
“Those who say they will die first and then rise are in error. If they do not first receive the resurrection while they live, when they die they will receive nothing.” - Gospel of Philip.
The empirical world is an illusion and it doesn’t exist independent of us.
“Do not suppose that the resurrection is an illusion. It is not an illusion; rather it is something real. Instead, one ought to maintain that the world is an illusion, rather than resurrection” - (Treatise on Resurrection 48: 12-17)
Humans do not have free will.
“For just as the Demiurge, secretly moved by Sophia (Wisdom), believes that he acts alone, so also with human beings.” - (Excerpts of Theodotus 53:4)
To sum it up we came from the Pleroma, we are going back to the Pleroma and this returning to fullness is inevitable.