Most fundamentalist christians, although believing that there is a hell and that people like me are destined for it, and want their religion to be right, probably would not want an approximation of their religion created conditional on it not already being right. An AI cannot make Bob right.
That being said, there probably are some people who would want me thrown into hell anyway even if their religion stipulating that I would be was not right in the first place. I should amend my statement: I want people to get what they want in ways that do not conflict, or conflict only minimally, with what other people want. Also, the possibility that there are a great many people like the Bob (as I said, I'm not quite sure how many fundamentalists would want to make their religion true even if it isn't) is a very good reason not to use the average human utility function for the CEV. As you said, I do not want Bob to get what he wants and I suspect that you don't either. So why would you want to create an FAI with a CEV that is inclined to accommodate Bob's wish (which greatly conflicts with what other people want) if it proves especially popular?
I wouldn't.
So why would you want to create an FAI with a CEV that is inclined to accommodate Bob's wish
It’s the year 2045, and Dr. Evil and the Singularity Institute have been in a long and grueling race to be the first to achieve machine intelligence, thereby controlling the course of the Singularity and the fate of the universe. Unfortunately for Dr. Evil, SIAI is ahead in the game. Its Friendly AI is undergoing final testing, and Coherent Extrapolated Volition is scheduled to begin in a week. Dr. Evil learns of this news, but there’s not much he can do, or so it seems. He has succeeded in developing brain scanning and emulation technology, but the emulation speed is still way too slow to be competitive.
There is no way to catch up with SIAI's superior technology in time, but Dr. Evil suddenly realizes that maybe he doesn’t have to. CEV is supposed to give equal weighting to all of humanity, and surely uploads count as human. If he had enough storage space, he could simply upload himself, and then make a trillion copies of the upload. The rest of humanity would end up with less than 1% weight in CEV. Not perfect, but he could live with that. Unfortunately he only has enough storage for a few hundred uploads. What to do…
Ah ha, compression! A trillion identical copies of an object would compress down to be only a little bit larger than one copy. But would CEV count compressed identical copies to be separate individuals? Maybe, maybe not. To be sure, Dr. Evil gives each copy a unique experience before adding it to the giant compressed archive. Since they still share almost all of the same information, a trillion copies, after compression, just manages to fit inside the available space.
Now Dr. Evil sits back and relaxes. Come next week, the Singularity Institute and rest of humanity are in for a rather rude surprise!