Voadam
Legend
Gygax?Actually, I am putting the creators of old school D&D as the arbiters of what makes sense in D&D. Other explanations are definitely possible, but IMO they should be used for other classes or in other games.
Gygax in Oe does not mention gods at all in connection with clerics. Nothing about gods in the entire cleric description. Gods start getting referenced in Supplement I Greyhawk in passing as beings but nothing connecting them to clerics. Even in Supplement IV Gods, Demi-Gods, and Heroes there is no discussion of any connection between clerics and gods other than some specific individuals having cleric powers.
Gygax in the 1e PH does say that "The cleric is dedicated to a deity, or deities," and that "All clerics have their own spells, bestowed upon them by their deity for correct and diligent prayers and deeds."
But in the 1e DMG Gygax reveals that first and second level cleric spells are not being granted by gods or supernatural beings at all in his default 1e D&D cosmology, third to fifth are being granted not by gods but by servants of gods, and gods only directly grant sixth and seventh level spells.
Moldvay in B/X Basic says that "Clerics are humans who have dedicated themselves to the service of a god or goddess. They are trained in fighting and casting spells. As a cleric advances in level, he or she is granted the use of more and more spells. However, clerics do not receive any spells until they reach 2nd level (and have proven their devotion to their god or goddess)." and then never mentions gods again.
And 2e has the full on spellcasting priests of non-deity forces and philosophies.