honestly... if it's a gold sink that can't be taken back out as gold, and if the stuff in the sink can be used to do religion related stuff (building, feasts, processions, relic expeditions, whatever), then people won't be using it as banks.
in short, probably every few levels should offer some exotic benefits.. (that is.. people pay a bit for the benefit, rather than just gratis)
people can pay gold to pray in a temple (really old temples from before religion) for morale boost or something, so why can't they do the same with player temples?
