I imagine they were filtered through - in order - Early Christian polemics, Renaissance magic, Theosophy, the Western Occult Tradition and various pulps from the 20s to the 60s.
It's not as though the game designers were consulting Origen.
Gnosticism is a very fuzzy word.
Nobody can agree about what was happening with religion in the first couple of centuries CE.
Well we know that Theosophy was an influence because Planatars and Solars Angels are borrowed from Theosophy, while Devas and Asuras are borrowed from Hinduism.
Of all the major Celestial races in D&D I'm not sure what mythological origin of Guardinals and celestial Eladarin are?