Gnostics proposed the God of Abraham (OT God) was evil, that Jesus wasn't actually there, and was simply the projection of a higher being trying to teach people that OT God was trying to corrupt them and trap them on Earth, and that salvation could be achieved by the individual through study, meditation, and very Buddist like concepts of perfect imperfection.
The Christianity that survived was simply better at killing Gnostics.
Because they want to escape "Christianity's chains" (Psalm 2) and because they wish to be a threat but they are not. Instead, Hell is a big threat for every one in the Notzrim and Mandaean's like herd but they don't realize that.
Since God is for us who can stand against us and how can gnosticism be a threat to Christianity?
Gnostics taught that only a few would be saved and it would not be salvation through Jesus but instead salvation through Gnosis or Knowledge.
Gnostics taught that Jesus was just a spirit in human flesh, that there was no resurrection, no crucifixion.
Gnostics also taught that the earth was the creation of evil aeon's or spirit beings and that Judas Iscariot was part of the grand design that he actually performs a service to Jesus so that Jesus could shed his earthly body and ascend to the heavens.
the gnostic Jesus is very removed from the Jesus of the bible , in several of the Gnostic scriptures he is seen as derisive, he does not perform miracles , he almost seems ambivalent to the plight of mankind and like in the gospel of Judas spends a lot of his time laughing at the apostles for being fools.
The gnostic texts are called gospels which is a total misnomer. Gospels are the "good News of Jesus the Christ" gnostic text have no good news about Jesus or anyone else.
Because by condemning matter they invented a belief system that completely denied the Incarnation, the Passion and Resurrection of our Lord Jesus Christ. Essentially denying the point of Christian Redemption, thus making Christianity pointless. The Gnostics kept on reappearing in the History of the Church. One tragic re occurrence of the gnostic stronghold currently cripples the vast majority of evangelical Christians who vehemently reject Holy Images representing Christ as He revealed Himself, in human flesh. What protestants cannot understand (because of the stronghold) is that when they reject a representation of the Word of God as a human being, they implicitly reject the reality of His Incarnation (even if they preach it) for what they do matters more than what they say. And if the Incarnation of Jesus Christ is denied, then so is His Passion (some marginal protestant theologians have actually questioned the historical reality of the Crucifixion) and without Passion, no Resurrection. We are back to the old gnostic nightmare. There is indeed a frightful connection between iconoclasm and gnosticism ; Orthodox Christians understood this and paid a very high price to correct it. The Western Christians have yet to discover the existential importance of Holy Images. As a result of this tragic error, protestants have also denied the Blood and Flesh reality of the Eucharist ; they think of It as a dis incarnate symbol (and unfortunately that is all they receive during their communion service). Christ warned us: "Amen, amen, I say to you, unless you eat the Flesh of the Son of Man and drink His Blood, you do not have life within you (NAB John 6:53)" it gets even more sad at John(6:66). I sincerely love my evangelical brothers and sisters but there is nothing I can do to break this stronghold.
The Gnostics were those claiming "Gnosis" -- the *direct* personal Knowledge of & from the Divine.
Christianity, as it became Churchianity, became a religion of idolatry -- idolatry of their own fallacious conceptual understanding of Jesus, which they mistook for being spiritual truth, &, in time, idolatry of fallible men's *words* -- which some of them apotheosized as the scriptures. It was not purity that apotheosized the Bible.
Contemporary Christianity, in largest part, continues to be a religion of idolatry -- of their beliefs about "Jesus" & of the Bible. It's an abstract idolatry -- an idolatry of a theology, of a belief system, thus is a considerably more virulent idolatry than merely idolizing a figure of wood, stone or metal (as witness the Crusades, the Inquisition, the "witch" killings etc.).
Gnosticism was such a threat because Gnosticism was *practicing* what Jesus taught -- to be going directly to the Holy Spirit for spiritual Guidance, rather than to other men (bishops, etc., or *any* scriptures, for that matter). If one had a deep relationship with the Holy Spirit (Who *some* ancient Gnostics recognized as being "She" -- IE, Sophia, Goddess of the All, Divine Mother of Yeshua -- tho different Gnostics called Her different Names, Barbelo, Protennoia, etc. & some viewed Sophia as being Christ's Divine Spouse, making a distinction between Mother Sophia & Daughter Sophia) one was living in genuine Gnosis.
The established Christian Church was the Church of the Christian Pharisees, tho it has never been known as such. They had the same legalistic attitude, which is really anti-spiritual. They could no more tolerate the existence of the Gnostics (some of whom had the True Holy Spirit -- cf. The Gospel of Thomas, The Gospel of Philip, Thunder Perfect Mind & Trimorphic Protennoia (in it's original layer, minus the latter additions), clearly all of these are mostly from Her Spirit) any more than the Jewish Pharisees & Sadducees could tolerate the existence of Yeshua. So, much as the Pharisees demonized Yeshua, called him a blasphemer, & got him crucified, likewise the Christian Church demonized the Gnostics; & when they had sufficient political power, centuries later, that part of Christianity eliminated the Gnostic Christians & their scriptures thru a massive bloodbath, with book burnings much as Hitler dealt with the Jews.
The War Against the True Holy Spirit has been waged by the majority of Christianity ever since (under the self-justifying-delusion that they were eliminating "heretics").
The Gnostics who recognized the Divine Feminine were an obvious threat to a patriarchally-dominated organization which was warring against Goddess and the Living Holy Spirit -- Who has always been Goddess, in reality.
Her Holy Spirit sets people FREE from the false teachings of the Church & the false teachings that *are* incorporated into parts of the (later) canonized Bible; & of course the Church, in seeking to control people's minds, could not tolerate that.
However, Goddess miraculously preserved many ancient Gnostic works (in the Nag Hammadi Library) -- that some of Her Larger Truths & Revelation -- from almost 2,000 years ago, can be known. Thus, now, Churchianity's distortions of the Gnostics can be recognized -- revealing Her Divine Presence in at least *some* of the Gnostic Writings to any with spiritual eyes to see.
This knowledge *helps* people make genuine spiritual contact with Her Living Holy Spirit *now* -- which is what Christ has always wanted for each of us -- that we know *Her* as *he* knows Her...