Doug McCrae
Legend
Regarding the arcane/divine split, the proximate source (@Northern Phoenix is right ofc that the demonic/holy split is much older) might be the novels of Randall Garrett. Jon Peterson, Playing at the World (2012):
In a footnote, Peterson quotes Garrett:
There are fantastic worlds where the distinction between a Magic-user and a Cleric is sharper, however. In Randall Garrett's Too Many Magicians (1966), a novel Gygax favorably reviewed, there is a sharp division of wizards into Sorcerers and Healers, the latter of whom are representatives of the various religious traditions.
In a footnote, Peterson quotes Garrett:
There was the dominating pale blue of the Sorcerers, modified by the stark black-and-white of the priestly Healers, and the additional touch of episcopal purple. The dark rabbinical dress of the occasional Jewish Healer was hardly distinguishable from that of a priest, but an occasional flash of bright color showed the presence of a very few Hakime, Healers who were part of the entourages of various Ambassadors from the Islamic countries.