Today I was listening to Father Petersen's favorite NPR show but only because his favorite NPR interviewer was not doing the interview. This comment on titles and names from character actor Stephen Tobolowsky caught my attention when it came to the Pastor First Name vs Pastor Last Name question:

If it's a comedy - now, this is not a hard-and-fast rule, but I've kind of found it to be true. If it's a comedy, you get your job description and your first name, like in "Wild Hogs" I played Sheriff Charlie. I played Ringmaster Bob, a lot of roles in which you get the job and your name.
If you are playing a serious role, you get the job description and your last name, Detective McClaren, Agent Jones. Now, then there's a level below that, in which you get no name, you get no name. You just get your - sometimes your job description - homeless man, man on train, man with a limp. You get these. These are usually not very good roles.

Yup, that's about right.

+HRC