You might find the Holy Grail traditions and the more recent Rosicrucian tradition interesting, if you're not already aware of them. These are, like Gnosticism, Western Esoteric schools. Esoteric, as in the in-group teachings, or occult (the hidden) teachings. I'm fascinated by all of it.

I'm currently into Rudolf Steiner, a highly-regarded Rosicrucian teacher that left behind many books that are available in English (he lived around 100 years ago), but his writings are sort of a dive off the deep end. They require a lot of open-mindedness, to say the least.

The "dark lords of the earth" who created the material world is a common theme: Steiner also called these the followers of Ahraman (misspelling that probably), they are then offset by the Luciferic beings (the light-bearers), who are on the opposite end of the spectrum. Both are considered similarly destructive in opposite ways. The former represents unbridled materiality, the latter unbridled spirituality. Then there are the middle beings, sometimes called the Michaelic, who embody the balance and thus are considered worthy guides. There's a holy image of Jesus on the cross with two thieves on either side, also crucified, one turning towards Jesus, the other away: this image is commonly interpreted as portraying this dark-balance-light framework.

Modern Christian teachings sort of reduce this three-point system into a simple duality of good and evil, light and dark: which completely misses the point of the earlier teachings. Both the dark can be too dark, and the light can be too bright, it's about the middle way. Or, in other words, light isn't necessarily good. Today Lucifer is associated with dark beings and is a synonym for Satan, which might be fine, except that it then suggests that a being is beneficial as long as it's not dark, which is not the case.

It's interesting to note that some scholars assert that other, seemingly unconnected religions (e.g. Tibetan) also recognize these same beings (using their own terminology).

I unfortunately don't have a reference, but I have it on good authority that you can find Jesuit writings where they openly talk about reincarnation, contrary to the outer-religion teachings. They also tought their missionaries the use of pendulums and dowsing to find drinkable water, food, medicinal herbs, etc. when they're alone in a strange land. There are books by at least one French Jesuit priest where he shares the techniques. The more you dig, the larger the discrepancy between the out-group and the in-group teachings. I love this stuff.

I over-shared I guess, but it was fun writing this.