To clarify my statement about only being identifiable while on official business, the pastors I know don't wear a collar while performing the service, but they do (or, rather, some do) put on a robe. After the service, they take the robe off and are in regular clothes.
Since we're all agreed that there would be quite a few churches to choose from I just wanted to add that if you *want* the person in your story to recognize the pastor/minister/priest, you could always have them be in a Catholic or an Episcopalian (sp?) church. (In which case, they'd call the priest "Father".) OR, you could have them be in church immediately before or after a regular service at the church of your choice, while the pastor still has his robe on.
- Vicki