Setting up your pantheon to get it to work. And how powerful is the god whose champion you are, anyway? And you have the issue of how much free will your character has got. Especially when you have questions of how often you bring the god on stage and how clearly.
Heard an amusing story about a hospital where two psychopomps showed up for one kid and had to consult with the only human who could see them as to which actually got to escort the soul off.