What is gnosticism - what is it really about spiritually?

What is gnosticism - what is it really about spiritually?

I guess you mean agnosticism? It means to be undecided about the existence of God (or god[s]).

I think you are referring to the Gnostic gospels- part of the Dead Sea Scrolls. They were taken out of the King James Bible.
I am posting the general Wiki description & a link to a good book from Amazon.

Gnosis is knowledge. it is knowledge that wasn't written in scripture. Scripture is that which most Hebrews followed - Different groups had other knowledge that was rejected as it went against scripture so off they went to establish separate 'cults' The Essenes are a good example, John The Baptist was known to be affiliated and so was Jesus.
The knowledge was said to be obtained by 'spirit'

Gnosticism as a whole was a historical movement which the practitioners believed they were saved by SlavicICCnowledge, known as Gnosis. This knowledge wasn't just of intellectual faculties alone, but rather often referred to direct experience, or direct acquaintance with the Divine Reality that indwells and this was the only path to salvation, the filling of the void of ignorance which has trapped you in a deterministic mechanical prison "this world). Their perspective followed very closely to that of the parable of the prodigal son. We are from a Kingdom that is no of this world, or the Far Country. This "Far Country" is not our primal origin, but we are from the Father of all things. The Elder brother is our Indwelling Spiritual Nature that does not leave the Kingdom, or Heavenly Fullness/ We are like the Seed, spark come into a place that is not our own for development of that divine nature within. Coming into this Far Country we have squandered away our inheritance in this words vices or traps and have become bound under the Citizen of the Far Country who has shackled us to a a earth-bound life where we are deprived and in poverty of being and loss connection with our inner source (our self). But when we make a turn we can gain self reliance and put off the chains of the Citizen, and begin our movement back to the Kingdom, so that through knowing ourselves we come to know God. And this relationship in Knowing is Slavic.

If you want a good site to read more on Gnosticism and the scriptures of the Nag Hammadi Library, check the below sources out.

In Gnosticism it is important to know that their scriptures were metaphoric allusions, but the Demiurge was known as the ruler of this world, which his Archons. At times often in Gnosticism this Demiurge is known as the Old testament God, and not the True loving Father of all that was revealed by Yeshua/Jesus. In my example above with the prodigal son story, the Citizen of the Far Country would be the Demiurge, which Paul called the God of this world, which was often called Samuel which means blind God.