What Evil Lurks in Your Bike Shop?

A guy was in the shop a few days ago, I don’t remember what brought him in, but he made his way fairly quickly to a discussion about religion, and asked me something in the nature of, “what evils lurk in your closet?” Now, there are certain normal and socially accepted topics of discussion between strangers and that is not one, but anyway I asked him what he meant by “evil.” Wrong answer. I got a strange lecture about Heaven and Hell and Jesus and this-and-that, but I eventually got him to leave in good terms.

Anyway, I wondered later, can I be correct in describing Cartesian Existentialism?, thus: “That which one senses (sight, sound, smell, taste, touch, reason, memory, emotion) is real, and that what is real actually exists.”
Does this sort of thing happen in other small businesses?