I wouldn't call confidence in your convictions gnosis, that's more a kind of arrogance and everyone suffers from that. However, I see how one could convince themselves of the other. Being so self convinced of a position that you feel it is absolute divine truth revealed through Gnosis. That is something everyone suffers from.

When it comes to spiritual stuff, that is why I don't subscribe to any particular cosmology or doctrine and only hold one simple thing to be the truth. God exists and is the totality of everything and everything is a part of it. I don't even like to call it God most of the time because words cannot do it justice. I've experienced that directly and that is all I know. The rest is all just theories and speculation that has been built upon, it's interesting to think about but isn't usually helpful beyond mental masturbation.

Now, is that self delusion and arrogance posing as Gnosis? Some might say yes but it's the one thing I'm 110% firm on, an experienced changed my life and I cannot feel differently about it. Nothing that I have seen or experienced since has led me to feel any differently, things have only solidified this 'faith'.

As to the details of this stuff, I believe that is why the Buddha rejected speculating about cosmology, even though Buddhists have cooked up complicated cosmologies and doctrines. It kind of is a 'cleaner' way to look at it for people that are bogged down in complex cosmologies and theologies, in my opinion, at least it was for me initially, but as I say, Buddhist doctrine becomes self defeating and full of crap that wasn't supposed to be part of the teaching. Buddhism and Taoism are not incompatible with certain Gnostic thought, either, but that's another subject.

Actually I will say this. Mainstream Christianity is pretty far removed from say Buddhism, and you would wonder how they could be compatible. In that sense, no they are not, they are completely different world views. Jesus is the only way to God and non believers will not be saved, they get purgatory at best (made up by the Catholic church) or hell at worse. It is the Gnostic side of Christianity that allows one to see the parallels in the Eastern traditions. To a mainstream Christian, this is blasphemy or worse, satanic. I personally find that ridiculous.

Also, I'm not trying to shit on anyone's personal beliefs here, because I do recognise people experience this differently and I've learned to see the common denominator and metaphor.

If you haven't already, learn about the the Nag Hammadi library and the dead sea scrolls, where some of the gnostic scriptures were found. The Gospel of Thomas is a short and interesting read. Hopefully you know how the Roman Catholic Church was created and why, and how they came to choose the 4 books to represent the new testament. The Gnostic scriptures were left out and they are of varying ages and legitimacy as far as authorship goes.

https://www.biblicalarchaeology.org/daily/biblical-topics/bible-versions-and-translations/the-gospel-of-thomas-114-sayings-of-jesus/