Vault City
Deliver Moore's briefcase to Mr. Bishop in New Reno.
Thomas Moore stands in the inner city preaching. If you play along, and providing Bishop is not dead, Moore will give you a briefcase to deliver to New Reno (which shows up on the map). If you happen to piss him off in conversation, you can always mollify him again unless you're a Slaver. Just don't ask him for payment or threaten to turn him in, or he'll put a note in the briefcase telling Bishop to kill you on arrival... which is bad. You get 500 xp and $250 for a successful delivery. Note that you must take this quest if you want to do missions for Bishop later.
After you've made the delivery and learned Moore is an NCR agent, you can turn him in to Lynette for 500 xp. I see no problem with this since Moore is a fanatic, you don't lose any karma, and Bishop doesn't care.
Slavers can actually get this quest providing they have CH 9 or Speech 96%.