inhabitants of the torrid zone, 1630s, from Medieval Latin Ascii, from Greek askioi, from a- "not, without" (see a- (3)) + skia "shade, shadow," which Beekes derives from PIE *skhieh- "shadow" (source also of Sanskrit chaya "shadow," also "image;" Persian saya "shadow," Albanian hie "shadow"). So called because they "haue the Sunne twice euery yeere in their zenith, and then they make no shaddowes at all" [Nathanael Carpenter, "Geographie Delineated forth in Two Bookes," 1635].
1670s, "belief in a deity or deities," (as opposed to atheism); by 1711 as "belief in one god" (as opposed to polytheism); by 1714 as "belief in the existence of God as creator and ruler of the universe" (as opposed to deism), the usual modern sense; see theist + -ism.
Theism assumes a living relation of God to his creatures, but does not define it. It differs from deism in that the latter is negative and involves a denial of revelation, while the former is affirmative, and underlies Christianity. One may be a theist and not be a Christian, but he cannot be a Christian and not be a theist. [Century Dictionary]
<a href="https://www.etymonline.com/word/sciotheism">Etymology of sciotheism by etymonline</a>
Harper, D. (n.d.). Etymology of sciotheism. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/sciotheism