This.
The problem with D&D is, that they try to make every class everything.
You wanna play a godless cleric and have all these cool powers but don't want any of the Baggage of actually believing in a god? Sure, go ahead.
Oh, you wanna be a cleric, but you like the Warlock class mechanics? Here, have a Unicorn as a patron. Oh, you wanna be cleric but Sorcerers have cool stuff? Be a divine soul sorcerer.
Like ...
D&D has introduced 3 types of origins of magical powers:
- learning
- borrowed
- innate (I would call it Mutation)
Arcane magic is usually learned or innate. Divine magic is usually borrowed. Innate magic - something is wrong/different with your body/soul to be able to just do it (ancestor was a dragon, went into a magical storm and came out changed ...)
That is the baseline.
So in my games if you want to have divine magic, you need to borrowed it from someone or somewhere external (doesn't even need to be freely given. Chain the unicorn in your wizard tower and drain it for blood to cast divine magic for all I care, at least you will make a good villain in the campaign).
If you want magic that just exist because of your believes - you need to play a sorcerer. Because that is the innate magic class.
An 5e Paladin explanation is just a mess.
So, in my game worlds, Paladins are either beholden to a deity/external power source, or they are basically sorcerer knights (innate casters).
The Warlock is the only one who actually thematically could have all three origins of power.
He borrows power from gods demons and devils.
He can learn magic, seeking out forbidden knowledge by making pacts with powerful beings who will bless him with knowledge or ... even worse: just learn it like a silly wizard, if the Warlock is intelligent enough for it.
Or he tries to change his body to get innate magic. Chugging potions to mutate, having a demon lord twist and transform his body to get him supernatural abilities and so on. - Warlocks want power and they take every way to get it.
- Borrowed Magic can be taken away but is also the easiest to get.
- Learned magic needs to be ... learned. It takes time, money, intellect
- innate magic is the hardest to get. You need to be born with it or something needs to happen to you to change your body (fall in the cauldron with magical potion as a child, having a mad wizard do magical experiments in you, have Cthulhu probe and expand your mind, or a mindflayer larvae implanted ...)
I'm working on some homebrew rules where characters can pray and get answers if they do it right, without needing cleric classes. Of course it is way weaker than normal cleric powers, but it is there.