It's a nice idea, but it does feel a little like medieval papal absolution - by which I mean it's an expression of the favor of the church/god(dess) tied to money. However, presumably the god (let's use Aeridin) knows if his follower is out grinding 24/7 and killing hundreds of creatures a day. By doing that PC XX has tones of items and money he can donate, but he got it by breaking church law left and right
. So in my opinion tracking donations is a nice idea, but to reward someone for them would have to be taken into account with their activity in game.
Just my 2cp!