We think the cleric in Dungeons & Dragons 5e is underpowered and that there lacks narrative coherence in the mythologies supplied. The following rules are our answer to both of these challenges.
NEVERBORN & ONCEBORN: There are nine greater gods (aka: neverborns*) and all the demigods (aka: onceborns) that the setting demands. Greater gods grants 9th level spells. Demigods only 5th level spells. Some demigods are "sponsored " by a greater god, thereby being able to grant 9th level spells. A sponsored Demigod changes its status from demigod to lessergod.
TEMPLAR, CLERIC & PALADIN: The priests of the greater gods are named templars and their places of worship temples. The priests of onceborns are named clerics and their places of worship churches. Paladins always serve a greater god and has the same advantages as a templar has over a cleric. Between a templar and a cleric there are three differences.
DIFFERENCES: 1) Templars add two levels to their Dispel Magic spell when targeting any cleric spell. 2) Divination spells cast by a templar gains the "expert divination" feature (phb, p. 116). 3) All undead has disadvantage on their saving throw versus a templars Turn Undead.
THE NINE NEVERBORNS OF THE D&D MULTIVERSE:
SEIZE THE DAY: (all divine-users): Divine spellcasters can forfeit the ability to prepare two of their spells, into the ability to seize any two spells instead. Whereas prepared spells are made available by preparing them beforehand, seized spells are made available by casting them in the moment. A caster can seize any of the many divine spells normally available for preparation. But from the moment the spell is seized, that spell counts as one of the available spells, and one less spell can be seized until a long-rest is made. Whether a spell is made available through preperation or through seizeing. It's still your spell-slots that decide how many times you can cast your availble spells.
Divine-spellcasters can only change one of their prepared spells per day.
CONCERNING DIVINE SPELLS:
Cleric spell lists:
Etherealness and Planeshift; see the cosmos post above.
Resurrection and True resurrection; is out (lack of consequence)
* The three evil neverborns are also named "the corrupters" & "the horsemen".
The six non-evil neverborns are also named "the elder gods".