The reason for my trust in it is not mainly based on archeology but rather that it quite accurately describes the process of ego-dissolution.
The ’world’ created by the Demiurge is the same thing as the Eastern religions call the ’maya’, meaning the illusion or play that is created by your ego-mind and the collective ego-mind. It basically states that the world you inhabit is an illusion of your mind, and that while you are in it you are that illusion. And that the apparent evil in the world is created externally by the collective ego and experienced as suffering by the individual ego.
It also says that everyone has access to ”the kingdom of heaven” which refers to a different perspective or state of consciousness, what the Buddhists call enlightenment and the Hindus call moksha. The ”kingdom of heaven” is not the same as the afterlife, but available right here and right now, as soon as you see through the illusion of a separate self, which is what the awakening actually is. You wake up from the dream of a separate and suffering little you.
That the truth is ”accessible to an enlightened elite” is not a fair statement. The Truth is all there is, always present and always available, in fact inescapable. The Truth is already here and now, it’s just a flaw of perception that keeps one from seeing it. Of course it depends on everyone unique life story and pre-disposition if they will experience it in this life time, but pointing out that fact does not make you responsible for it. Understanding the theory of relativity is theoretically a possibility for almost everyone, but in reality it is currently mainly understood by a small elite. Pointing that out does not make me or physics teachers inherently evil. The criticism of Jesus was just that, that the faiths at the time were actively hiding the truth from people and in many if not all cases did not even know the truth themselves.
Once again ”enter into heaven” means liberating oneself from the ego, and in the language used here ”makes herself male” basically means make herself a spiritual being. At the time spirituality was not allowed for women, who were of course considered the source of all sin and basically on the level of domesticated animals regarding social rights. The very fact that Jesus taught women and said that they could become equal to men should be taken as an insanely radical statement of egalitarianism, unheard of at its time, not as a slight upon women.
Gnosticism is valid from the only two viewpoints I am interested in:
-Providing methods for enlightenment
-Describing how the universe works
Your idea that Gnostics would have caused as much bloodshed as Islam or Christianity is just an angry opinion expressed without any facts to back it up. If they would, it would at least not have been possible to support the actions with their teachings. Unfortunately we will never know.