I live in Nashville (AKA Bible Belt) and we get asked all the time thinks like, "Where do you go to church?" or similar questions. I stopped telling people that I am not interested, I now tell people that I recently moved to the area and that I am looking for a church like my last church which was clothing optional. Typically the conversation ends right there.
Say 'have a good day' and walk away.
Say leave me alone or my foot will put you that little bit closer to god
Say "I'm NOT Interested. Now if you'll excuse me I have to get back to planning my gay wedding."
I would have told him I'm already on board.
I had one of these people approach me in a park. I had to leave.
I'd tell him what Jesus would do. Jesus would tell him that actions speak louder than words.