However in D&D, gods are the interface between morality and you so you have to be a paladin for one of those.
You are describing Cleric ...
By sticking closely to a vow, you would slowly be able to tap into that energy, kinda like weave.
I allways thought that Paladins draw their power from themselves ... like a Sorcerer ... but there isnt nearly as much of it, and they only can reach it as long as they believe they can reach it ... therefore there is Oath.
After all, if they break it, they can still reach Magical Powers ... just different one.
Shouldnt they loose all magical power completely, if it would be provided by some deity?
