As I mentioned before: in all of my years DMing, I have seen exactly two clerics who have shown anything more than lip service (if that) to their deities. One of those clerics is currently being played in my AD&D 1st edition game. (We had our fourth session last night) Two of the cleric's vows are proving somewhat troublesome for him in terms of experience points:
1. He may not partake of anything that influences the mind (So no gold can be spent on carousing, for which I award bonus xp)
2. He may not take anything that he hasn't earned, which means that he often refuses his share of the treasure if he believes it wasn't earned. (He equates it with stealing) This has so far denied him some xp. (However, the other party memembers often "pay" him for various services rendered as a way to talk him into taking gold. That, and the fighter/thief keeps paying for the cleric's lodgings)
Now, the player did create his own deity and decide upon these limitations, so they are self-imposed and willingly accepted. I know a fair number of DMs who would take the "let him eat cake" approach, but I disagree with this, because this is finally a cleric who acts like a damn cleric, and I'd hate to penalize him for it. One player has suggested that I "arrange" for acceptable loot or gear to be found, but I am also opposed to this, as it invalidates the religious vows that the players invented and has his character adhere to.
My thoughts are this: perhaps the cleric should get experience for the treasure he refuses. After all, coudln't you argue that adherence to his vows actually strengthens his faith as a cleric?
As I have stated before, clerics are the class that most players (in my experience) are reluctant to play, and I think a player should be rewarded, rather than punished, for not only playing a cleric, but playing him with actual limitations placed on his behavior.
...and you know, the more I discuss the subject of clerics, the more I like the notion of the Lay Healer profession in Rolemaster. (Which I haven't had time to peruse at length, but seems like an interesting alternative.)