I think, if you are persuasive enough, you might be able to persuade someone to do things that might be against their morals. Here's the problem, it's not going to be one check.
If it is something that is against their morals, like the priestess, it might take many, many private conversations, over an extended amount of time (weeks, months or years) against a dc of 'hostile NPC'. (Even though the Priestess, herself, might not be hostile)
A success might nudge that NPC towards less hostile or Indifferent. In other words, your arguments have managed to sway them enough to doubt their beliefs or, at least, see another perspective. It certainly won't make them go against their vows.
Then, after more time and discussions, you might be able to move them to a 'friendly' disposition. At this point, you might be able to convince them to break their vows. Maybe You've earned their trust and, possibly, managed to make them fall in love with you.
I wouldn't let a single roll in a single night dictate an outcome like that.
So, before you have them roll, ask yourself this: what is their disposition towards what's being asked? How long will will it take to change said disposition? Do they have enough time?
If there's an NPC looking to for a good time and wanting bring someone home for the night, it might only require a 15 minute conversation and a roll against 'friendly'.
So, if you get ambushed by bandits, you might be able to persuade the bandit leader to let you live and maybe let you keep your wedding ring. There's no way you're going to convince him to give you all his stuff and be your bff.
I don't let players roll against other players unless the other player agrees to what is being rolled and is uncertain of how their own character might react. Or, if it's a combat happening (which is rare) like one PC is grappling another(maybe his buddy is charmed), I might let them roll persuasion to escape the grapple instead of athletics as he 'persuades' his ally to let him go.