Explain what gnosticism is?

Gnos·ti·cism

noun /ˈnästəˌsizəm/

A prominent heretical movement of the 2nd-century Christian Church, partly of pre-Christian origin. Gnostic doctrine taught that the world was created and ruled by a lesser divinity, the demiurge, and that Christ was an emissary of the remote supreme divine being, esoteric knowledge (gnosis) of whom enabled the redemption of the human spirit.

Gnosticism is hard to define, very hard. A lot of what we do know about the early Gnostics were written by the early church fathers who were anti-gnostic. (St. Irenaeus, St. Hippolytus, Tertullian, et al.). The different gnostic schools of thought viewed the creator god on a scale. Some sects viewed the demiurge (creator god) as completely evil other sects viewed the demiurge as just ignorant or imperfect. But all ancient Gnostic sects believed in a unknowable god referred to with a multitude of monikers such as The One, Monad, Pleroma, etc..

To achieve salvation from the material world Gnostics had to seek Gnosis which is even harder to define. Gnosis can be seen as "epiphanic insight into oneself". Gnosis is a Greek word meaning knowledge this can be misleading cause it implies factual knowledge. A more describing term would be enlightened or enlightenment.

I hoped I answered your question succinctly.

Well, literally it is knowledge of god.

It is also a title used by sects who looked at the world, decided that it was not perfect, and so could not have been created by a perfect being, and so the Earth and everything on it must have been made by the devil.

Presumably God gave us free will so that we could rise up above the devilish world around us.

It is a position that does not make much sense to me. But it does make more sense than the standard Christian one.

Of course the Church at the time did not like people saying this - so they killed all of them. After torturing some of them first.

Gnosticism is the preaching of special knowledge that is not found in the scriptures (and usually conflicts with what is in them).

its a position on knowledge, being a gnostic theist, means you KNOW god exist (its not a belief), its also possible to be a gnostic atheist (you KNOW god doesnt exist)

usually gnostics tends to be moronic people, convinced that their own opinions is proof

it's a silly way of avoiding questions by claiming personal special knowledge of the nature of god

It's the notion that we can know for sure whether gods exist or not.

I'm not buying it.