Divine Beings are fundamental in any fantasy world.
They grant spells and powers to some classes (such as Cleric, Druid...) and grant also many plots for your campaigns and adventures.
You must create and describe them as soon as possible.
Let's see how to do.
Create just a few (no more than 3-4)
As usual, it doesn't worth to write pages and pages filled with informations and rules which your players won't never use.
Create more than one divine beings, to give players some choices, but never more than 4, at least at the beginning.
You need to write just very few lines:
- Name and a brief description
- Its alignment and its followers'
- portfolio and areas of interest
An interesting variation is to create two different churches for the same divine being.
Choose divine beings' natures
You don't need to have gods like the classical Greek or outer plane dwellers like those of Forgotten Realms or Greyhawk settings.
D&D worlds are plentiful of other examples, such as Birthright gods, once mortals who have been invested by divine essence of the previous dead gods or Mystara's Immortals, once mortals who have risen to a greater level due their actions.
Or maybe the gods could be no more than powerful forces of the world, without an effective counsciousness or a physical form.
Choose divine powers
According the deity's description, choose spheres and granted powers (for edition until 2.5) or the available domains (for newer editions like 5E).
You can add other powers according to your desires or devise new domains if you think you need it.
Describe at least a Myth and a Rite
For every deity you must create something important about it.
A legend, a myth about world creation or its birth, an important holy day or something else.
A few lines are enough.
Describe church hierarchy
Choose for every deity if it has a complex church organization or if its clerics are only loosely organized or if a church doesn't exist at all.
Choose other religions/deities
The steps above are only for divine beings available for your Cleric and Druid characters.
You can create more deities if you want but for those you should write only their name and portfolios.
You'll develop them (if you need) as your players will explore your world.
Waiting for a new post work about deities of your world and, if you need any suggestions, use these ideas:
The Divine Principle: it's a force that guide and protect The Unique World. Its main prophet was the Master, He who nobody can tell his name, who had appeared a few years after the Demons came. He converted many (mainly Dròtnar and Dwarves) with his great divine powers and he was able to defeat a lot of Demons. He disappeared in a cloud of fire and his disciples found a little girl in his place. She was the first Lochia, an eternal incarnation of the Divine Principle, which every time reincarnates itself in a new baby girl until her mortal death, and whose only presence keeps at bay the Demons and protect The Unique World.
The Old Religion: its members (druids and clerics of the nature domain) believe that Gaya itself is a deity. They revere nature in any of its aspects. Their holy days follow nature cycles. It's main followers are among Dròtnar and The Tormented Lands.
An'Yan: the Sea Father. A sea deity worshiped by islanders of the Middle Sea.
Elemental Cults: cults about elemental worship (Fire, Water..) Dìar follow Fire while Ice Men those about cold.
Demons: Demons grant to some of their minions powers as Cleric or Warlock.