Ah now that you must be neutral (if you want that Cleric dip) you wouldn't qualify for Sacred Exorcist.
Well, I can be within one step. I plan to be Neutral Good. But the problem remains that the 'Church of Boccob of Latter Day Knowledge' wouldn't necessarily be interested in granting turning/exorcism powers. At least not in the same way that a church of Pelor or Hiernoeous would. Or the same way Obad-Hai would (because undead are so unnatural).
Also, can you tell us all of these role play requirements? It'll make it easier for us to give suggestions and come up with justifications.
Some of them I can't say because people in my group might bump into these forums if they start looking for info on the archivist when they find out there is one in the party and bump into this thread, finding out things they shouldn't know.
Anyway, here is what I can tell you.
[spoiler]There was a major catastrophe in the not too-distant past. My grandparents were oracles who were critical to restoring order. My family is a well-respected family (Think of them like the Kennedies or Bushes) an so let's just assume then they are scrutinized by the general population.
A generation passes.
My character, an adult, has had to do his mandatory military time. This is where that backstory level level comes in. I can either have fulfilled my actual military duty or have run to avoid it. Runing to avoid it seems impossible because I later have to work for this very same government, as I'll explain later. Anyway, I opted for something different -- the diplomatic route that noble-types might send their children on so that they don't die in the army with the riff-raff. DM strongly suggested that I would have gotten an adventuring level at this point.
Normal Life
A few years in the past, something mysterious (I actually do not know what) happened to my character. He had to be rescued by the 'FBI'. He was given the option of having his mind erased or working for the organization. Obviously, I didn't choose the former, or I'd be a farmer somewhere. My natural talents can lead me to whichever class I want to apply myself to, but Archivist fits the bill.
[/spoiler]
So as you can see, my military time is what is causing me grief because I couldn't have started off as an archivist, yet feel obliged to create a level for that time spent in service, whether martial or diplomatic. The archivist s an option that only realistically opens up for me when I join the 'FBI' years later. What makes the most sense is that I was off somewhere studying and became an archivist within the past few years when I started to work for this government agency.
This is just me, but did you ask for those restrictions or is the DM just coming down on you?
Originally, my character was supposed to be an NPC, but then the DM had the idea of introducing ME as the NPC so I could play over Skype from time to time (I moved to another state). That then turned into me playing the NPC as a PC for the whole campaign. So all of this is not so much him coming down on me, but rather the price I pay for being an NPC (who had those major elements set in stone) turning into a PC (which means I have to flesh this out). I'm a plot device.
None of the other players have these story restrictions because they were always PCs from the start and they didn't have their part written into the game's exposition. Perhaps a better option would have been to keep the NPC an NPC and I could start from scratch as a PC... then again, now I'm somewhat attached.