I was tickled by this myself. It's close to one of my core ideas in The Echoes of Heaven Campaign Setting (small plug, http://enworld.rpgnow.com/index.php?filters=0_0_0&manufacturers_id=729). We'd say, however, that you merely need to convince the other clerics or paladins that you are the right alignment (since there's no detect alignment in 4th ed, I guess that amounts to the same thing). We also added a ritual in 3.5 in an upcoming book that allowed them to strip you of your power. We didn't just want to have the possibility of clerics and paladins going rogue, but we also wanted the possibility that if your superior in the church hated you, you might have to play good with the politics as he tried to come up with excuses to strip you of power.
I think anything that adds conflict to a setting is a GOOD thing.
I think anything that adds conflict to a setting is a GOOD thing.