A paladin merely adheres to the will of his deity and is granted aid and powers.
I dunno, seems weird ...
What would make them different from cleric then?
Honestly, the very concept of the Oathbreaker makes no sense to me
Even if you strike deity out of that equation?
It makes sense to me ...
Paladin believed that he is worthy of power ... therefore he had power ... then he did something that made him feel like being unworthy of that power ... so he lost the power ... except he didnt in fact the power was still there, just malformed, twisted.
Or siplified version:
As long as Paladin believes to be pure (oath here works as set of rules that define purity) ... his power is pure ... once he lost that believe (aka break his oath) ... his power bevome twisted, bcs he is no longer pure.
If Deity would be source of his power ... besides being Cleric in fact ... he would lost his power by breaking his Oath, wich isnt happening.
Well back in 3.5 Paladin had High BAB, while a cleric had medium BAB. The difference between the classes was that a Paladin was more focused on physical combat, while a cleric was more focused on magical combat. Now this is no longer a valid differentiation, because BAB is gone (afaik), which is why I basically just play a cleric now, the Paladin lost it's salt in 4th and 5th Edition. In essence, the differences between cleric and Paladin were watered down enough to the point where one of them had to change in order to differentiate them. The problem witht his is that the Paladin was changed in a way that intrudes on the ranger's domain and thus the ranger lost it's identity and is still one the classes that is not exactly well handled by 5th Edition.
As for the Oathbreaker, I think it's not really a paladin. A paladin is a divine knight, an Oathbreaker however is more like a witch-knight. More like a sith lord in a medieval setting really.
I think the difference between a paldin and an oathbreaker is the source of their power. That is enough of a reason to handle them as separate classes, if it was not we could just call all caster-fighters paladin (including spellblades, rangers, bards, eldritch knights, etc). Basically, if you break your oath you do lose your power, it's just that game-mechanically you are de-facto relegated into the Oathbreaker class, so you don't experience a loss of power, like you would back in BG2, where losing your powers meant that you were basically a sub-par fighter.
The root of identity is not in game mechanics, but in the lore of the class. A Paladin is and always has been a servant of divine forces. You can try to twist the class into something else and still call it a paladin, but people will naturally notice this and move on to other classes that fir the archetype (namely, the cleric).
