I got the Molag Bal quest in Skyrim, where he wants me to lead the priest to his altar and then kill the priest. When starting this quest I felt certain that there must be, at some point, an option presented to betray Molag Bal and side with the priest instead. He's the god of betrayal/treachery after all, isn't he? So it seems fitting that there would be an option to betray him.
However it seems like no such option is ever presented. Is it possible to side against Molag Bal, and if so, how? If not, then isn't this quest pretty much broken? I mean, what's the option for playing a "reasonably decent" character if there's no way to refuse the god of evil and betrayal once he has you in his web?