Sorry, can you rephrase the question? I read that and think, "Who says they're not allowed? Not allowed by whom? Why is he asking me this question?"
Forgive me if I got the wrong person, but somebody (I thought it was you) started a conversation about 'paladorcs'. Most assumed that this was a portmanteau of 'paladin' and 'orc', but it was made clear that it was 'paladin' and 'sorcerer', with more P than S.
Then they said that this wasn't allowed.
If it wasn't you, I apologise.
So, to whom it may concern: why are paladin/sorcerers 'not allowed'?
I get the idea that by "evil party" you mean something other than "party that has evil PCs in it." E.g. you could have a party of heroes who goes around protecting their country and saving maidens from dragons, but also torturing those enemies for information or fun and taking unfair advantage of those maidens' gratitude (and their families') and making fun of retards and generally acting like Captain Hammer. And they'd be evil, but not what you seem to be describing as an "evil party."
So what was the point of the rest of your statement?
Explanation. Why I don't like playing clerics.
One of the things I really liked that 4e did, was make divine powers inherent. It opened up all sorts of opportunities for villains and heroes both; the rebel who turns against his orders and now uses the divine power of the gods against them.
Does a couple things...takes away the veto hammer from the DM (or rather, makes the veto hammer no larger on the cleric than on the fighter), and lets a player come up with his own motivations.
Plus, I just love the "backsliding priest" and "Chosen against their will" storytelling tropes, so it's fun for that.
When I dm games, I let the players make up their deity themselves. In ancient times, often each village, hamlet, city, and so forth, would have their own tutelary deity. No reason why we can't have the same sort of thing in D&D. So choosing a Deity becomes no more important to the campaign world than choosing the name of the village where one was raised.
I'm rather directly oppisite of you here.
Divine power does not come from within you, it comes from a divine being/force. So if you pick a class that's powered by the divine? Then choosing your patron IS important. (Doesnt matter what god you pick) As is following its tenants. And if you stray from the path too far/too often? Then you'll lose those powers.
It's a simple equation: Do _______, receive dayly allotment of power. DON'T do ________, don't receive power.
If you can't handle this? Then you shouldn't play a divinely powered character. Or at least not expect to have any powers.....
Except that in 5e that is no longer the case. While you may choose a god, there are now no longer any rules in place that cause a cleric to lose them if they stray from their faith. From memory, these rules were part of the cleric and paladin class in 2e and, presumably 3e. For 5e, divinely powered characters losing their spellcasting abilities would be a houserule.
A barbarian who becomes lawful would lose the ability to rage, and a monk who becomes non-lawful cannot gain further monk levels (in 3.5, at least).I wonder how many DM's who force clerics and paladins to follow their mandates and enforce this, also do so for all alignment restricted classes. I've heard all sorts of anecdotes of fallen paladins and even clerics stripped of their powers, but, I cannot recall a single instance of a barbarian losing his rage powers for being too lawful. :/
Oh yeah, that oath from the DMG, I often forget about that one. I kinda wish it was in the PHB, but do somewhat understand why it is not. The Death domain I think should have been in the PHB though, no real reason to leave that for the DMG when other death gods exist which aren't villainous.